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  #1  
Old 23-April-2007, 18:55
everton66 everton66 is offline
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Default PC Keeps Rebooting

Happens intermittantly on my son's PC. Worked fine all day yestaerday but today everytime the PC is switched on and he selects his name from the logon screen, seconds after logging into his account the PC just switches off and reboots.

This has been happening over a period of a few weeks. One minute it's fine, the next it goes into a reboot cycle and just keeps rebooting. Tried booting from last known good config and restoring to an earlier point - no luck.

I know it can be any number of things - PSU, RAM etc - any way to narrow it down?

Thanks.
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  #2  
Old 23-April-2007, 20:32
Austin_KW
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Default Re: PC Keeps Rebooting

Get yourself a live linux distribution such as damn small linux or knoppix. This will give you a bootable CD, If it boots, and you can access your disks, network, usb then its is probably software. Either way this often allow you to backup you files if a reinstall is necessary. Everyone with a PC should have one of these on the shelf, they can often get you on the net and access you files when windows throws its rattle out of the pram.

And get yourself a memtest86 bootable ram tester, Some Live linux distributions may include this as a boot option.

Also consider disk recovery programs. spinrite is a good one but it is commercial software (about 50 I think)
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Old 23-April-2007, 20:42
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Default Re: PC Keeps Rebooting

is the PC connected to the i'net, if so try disconnecting it and see if it is stable like that?

Sil
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Old 23-April-2007, 21:48
everton66 everton66 is offline
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Default Re: PC Keeps Rebooting

Get yourself a live linux distribution such as damn small linux or knoppix. This will give you a bootable CD, If it boots, and you can access your disks, network, usb then its is probably software. Either way this often allow you to backup you files if a reinstall is necessary. Everyone with a PC should have one of these on the shelf, they can often get you on the net and access you files when windows throws its rattle out of the pram.

And get yourself a memtest86 bootable ram tester, Some Live linux distributions may include this as a boot option.

Also consider disk recovery programs. spinrite is a good one but it is commercial software (about 50 I think)
Originally Posted by Austin_KW View Post
Thanks I will give that a go.
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  #5  
Old 23-April-2007, 21:49
everton66 everton66 is offline
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Default Re: PC Keeps Rebooting

is the PC connected to the i'net, if so try disconnecting it and see if it is stable like that?

Sil
Originally Posted by silver View Post
Connected via wireless. Reboots before the wireless connection happens.
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  #6  
Old 24-April-2007, 10:18
adie_gibson
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Default Re: PC Keeps Rebooting

I had this problem on 2 other pc's and found that if I flashed the bios it seemed to fix it,May want to check leads from motherboard to hard drive.
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  #7  
Old 24-April-2007, 10:51
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Default Re: PC Keeps Rebooting

to me it sounds like a virus problem, rebooting is common with certain types of internet worm / network worms

I would make sure that the PC is not networked / connected to i'net or other computers and see if it still does it,.

virus scan from alternative boot might be worth a try

Sil
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  #8  
Old 24-April-2007, 10:59
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Default Re: PC Keeps Rebooting

PS, it could also be an overheating issue,. does the PC reboot itself when just turned on but not logged in (if so it does point to a virus issue)

if it reboots when just switched on then check things like fans are spinning - take the side off and visually inspect when switching it on
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  #9  
Old 24-April-2007, 11:49
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centaur centaur is offline
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Default Re: PC Keeps Rebooting

In addition to the solutions already mentioned ( overheating, possible virus/es ) there is another possibility, that of improperly seated or damaged RAM sticks. Whilst the side is off checking for operating fans, and assuming they work ok, switch off, wait a while and check that the RAM sticks are fitted properly.
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Last edited by centaur; 24-April-2007 at 17:40. Reason: typo
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  #10  
Old 24-April-2007, 17:34
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Default Re: PC Keeps Rebooting

I had a similar problem and thought it might be overheating, but after checking I found it wasn't. Then I thought, as Centaur suggests, it might be a problem with my RAM, so I replaced it and since then (touch wood) problem solved.
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  #11  
Old 27-April-2007, 12:44
Olozzj
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Default Re: PC Keeps Rebooting

In addition to the solutions already mentioned ( overheating, possible virus/es ) there is another possibility, that of improperly seated or damaged RAM sticks. Whilst the side is off checking for operating fans, and assuming they work ok, switch off, wait a while and check that the RAM sticks are fitted properly.
Originally Posted by centaur View Post
When this sort of problem happens, RAM is usually the cause. Trust me, i see this virtually everyday, as i work in a computer shop. This could be a virus issue, but i very much doubt it becuase the problem is intermittant, whereas if it was a virus this would happen constantly.

PS when you're not connected to the 'net this problem may not happen. However, you must remember there will be less resources and less banks of memory in use here, so it still could be the memory if this happens.

Personally, i would try the RAM first over anything, but it is up to you.
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  #12  
Old 27-April-2007, 17:06
everton66 everton66 is offline
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Default Re: PC Keeps Rebooting

I download Knoppix and tried to boot from that but got loads of read errors. The reboot seems to happen after the same period of time - whether I have logged on or not. If I leave XP at the logon screen it will reboot after a certain period. If I log on it will still reboot after the same period of time - i.e. time since switch on.

Now - I have 2 sticks of RAM in the machine. I removed each one in turn yesterday and got to a point where it didnt reboot. Not sure if this has solved it because the reboot happened intermittantly, but so far so good.

Kaspersky reports no viruses.
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  #13  
Old 27-April-2007, 20:38
everton66 everton66 is offline
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Default Re: PC Keeps Rebooting

Hmm. After removing RAM, the PC booted up but froze when got to the desktop. Swapping the RAM resulted in the PC booting but not making it past the XP splash screen where you have the blue blocks moving from side to side. I then put all the ream back in and got the following errors:-

"Hard Error"

And then an error - red writing in a DOS type box saying "No Hard Disk Found".

Help!
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  #14  
Old 27-April-2007, 22:07
Austin_KW
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Default Re: PC Keeps Rebooting

Hard disk failure should not have prevented knoppix from booting could be a bad iso or burn. Sounds more like ram. Did you try memtest86+ (dont remember if it is a boot option on the knoppix cd).

Also try different memory simm slots if available & swaping the memory into a different pc. Or swapping in 'known good' ram from another PC.

Check the site for your hard drive manufacturer, some of them provide a bootable CD/floppy for basic drive testing.
Many of these and memtest and other diagnostic tests are included on the ultimate boot cd http://ubcd.sourceforge.net/
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  #15  
Old 29-April-2007, 17:47
everton66 everton66 is offline
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Default Re: PC Keeps Rebooting

I am currently doing a "memtest" on the RAM. 3 sticks totalling 386mb. It has been running now for well over 4 hours. It is 88% through task #6. It so far has 5 passes and no errors.

Does anybody know how long will it take to finish?

Thanks.
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  #16  
Old 29-April-2007, 17:52
everton66 everton66 is offline
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Default Re: PC Keeps Rebooting

It's OK - found the answer and other info:-

- How long does memtest run? How do I stop it?
Memtest runs indefinitely unless you stop it. It does however repeat the same tests over and over again. Memtest86+ contains a number of different tests which each take different approaches in trying to expose any errors in our memory. In the top right of your screen you can see the progress of each test in the lower of the two progress bars. The topmost progress bar shows the progress of a pass, each pass consists of all the tests in the memtest suite. Thus all tests are executed in one pass, so does that mean that no errors will show after the first pass if that pass didn't reveal any errors? Well no, there are several reasons why errors might only show up after a number of passes. Firstly as of this writing, the latest version of memtest also includes a test which uses random test patterns, each pass these patterns will of course be different. Secondly some types of errors simply don't show up until the system has been running for a while or are very critical on a certain timing condition, or other such conditions.

To conclude, one successful pass of memtest will give you a pretty good idea that your memory is ok, only in rare cases will there be errors showing after the first pass. To be sure though simply have the test run overnight or even for a couple of days depending on the level of importance of the system.

- How many errors are acceptable?

No errors are acceptable. Even if there is just one error, something is amiss which can cause your system to crash. Of course what the cause of the errors is you will still have to determine.

- What do I do when I get errors?
Firstly, don't start drawing any conclusions. You only know that memtest86+
is giving your errors, not what the cause is. Unfortunately it is not a straightforward exercise to decisively test the memory in an actual system. This is because a computer is not just built up of some memory, but also includes many other elements such as a memory controller, cache, a cache controller, algorithmic and logic units, etc, all of which contribute to the machine. If there are faults in any of these other parts of the computer you will likely also see errors showing up in memtest.

So what to do?
First verify that the BIOS settings of your machine are correctly configured. Look up the memory timing settings applicable to the brand and type of memory modules you have and check they match your BIOS settings, correct them if they don't and run memtest again Ok, you have all the settings correctly set and you're still getting errors. Well of course very likely causes are the memory modules and the logical course of action is to look into them further.

If you are well stocked, have a few other machines at your disposal, or just want to spend the cash for some new modules the best way to test if the cause are your memory modules is just to replace them and test again. If you are less fortunate though there is still something you can do.

If you have more then one module in your system, test them one by one, if one is consistently giving errors and another is consistently showing no errors it's a pretty good bet that the module giving the errors is simply defective. To exclude the possibility that a defective slot is throwing your results, use the same slot to test each different module.

If each module by itself shows no errors, but when you place two or more modules into the machine at the same time you do get errors, you are most likely stuck with a compatibility issue and unfortunately there isn't a whole lot you can do about it. Be sure to check your computer/motherboard manual to see if the setup you are trying is allowed, some boards require special restrictions in the sizes of modules, the order of modules, the placement of double sided and single sides modules and more of such things. If you have only one module in your system, or all modules are giving errors, there are only very few options left. The only thing you can do really is to try the module(s) in another slot. Finally simply try out different orders of the memory modules, although your manual might not mention anything on the matter sometimes there simply exist timing or other issues which can be resolved by changing the order of your modules. And of course test each slot by putting a single module into that slot and running memtest on it.

In the end if you still have not been able to localize the problem you will have to find a replacement module to establish whether the problem lies in your modules. See if you can borrow a module from someone else. When you have replaced the memory by new memory and the errors still persist, first check if you can rule out any compatibility issues or timing issues. If you are sure the memory should work in the system the cause of the errors must obviously lie someplace else in the system. The only way to find out where; is by trial and error really. Simply start replacing and/or removing parts of your computer one by one, running memtest each time you changed anything, until the errors are resolved.

- I'm getting errors in test #x, what does that mean?

Interpreting memtest results is as scientific an endeavor as testing whether a person is a witch by the methods used in Monty Python's Holy Grail. In short, don't even start; it's not going to get you anywhere. Just interpret any error as you should any other and use the methods described in the previous question to determine the cause.

- I'm getting errors in test #5 and/or #8 and have read a lot about it.
Yes there are just about enough discussions on the topic to fill a book, but it all boils down to the answer given above. The only thing that can be said is that many times, when memory latencies are incorrectly set in the BIOS you will experience errors in test #5 and #8. (Though #8 does not exist anymore as of version 1.40 and might be reinstated as a different test in a later version.) This does however NOT mean that errors in these tests are always the cause of incorrect settings; your memory might just as well be defective. However, if you have a failing module they will usually fail in test 4 no matter what frequency you run them at or at any given clock setting. And failures in test 5 or 8 usually would suggest that either one of a few things:

A. The settings are too tight or to aggressive for your system, IE not every MB can run with Cass timings of Cass 2-2-2-5 at DDR400 like with our XMS3200XL modules, and maybe relaxing the timings to check for this would be prudent to test. Try Cass 2-3-2-5 with the Rass to Cass set to “3” for example

B. You may have an un-stable power supply for your system configuration. Make sure that you have the correct type of PSU (Power Supply Unit) and that it has enough power for your system configuration.

C. All of our modules are rated up to 2.9 Volts, and in most MB’s I would suggest 2.7X volts with Most of our modules. In the case of our XMS3200XL modules and faster the minimum voltage would be 2.75 Volts. So you may want to look your specific modules part# up in XMS Qualifications and Testing (http://www.houseofhelp.com/v2/showthread.php?t=33521) to see if there are any voltage and/or MB requirements. Like adding extra cooling.

D. One of your modules may be failing, but that would or should become apparent when testing then individually.

- I'm getting errors in memtest on one machine, but not when I put the same memory in another, what does that mean?

It can mean one of two things:
- The machine that is giving the errors is defective. Errors don't just originate from the memory module itself, but can also be caused by defects in the CPU, chipset, motherboard, PSU and even by timing issues introduced by any other component in the machine.
- The machine giving the errors is imposing stricter timing than the other which the memory module simply can't cope with. If the module should work with the machine according to its specifications then it most likely is defective.

- Which memory is tested?
As much as possible of the system memory is tested. Unfortunately memtest86+ can usually not test all of the memory. The reason for this is that today’s processors have become so complex that they require a small amount of memory to keep accounting data of the processor state. If memtest were to write over these areas the state of the processor becomes invalid and it's behavior unpredictable. Alas it is also impossible to relocate these areas in the memory.

This means that a small area of your memory can not be tested by memtest. If this part of the memory is defective you will know soon enough though as the processor, or parts of the processor simply won't work correctly if this part of your memory is defective. Do realize though that in very rare cases memtest will show no errors even though the module is defective, not because memtest can't detect the error, but because memtest can't test the area the error is located in.

- When I select BIOS-ALL I get many errors / my machine crashes.

This is normal. With today’s computers this option should never be selected. See the previous question about the reason for the errors.

- Memtest freezes or my system reboots when running memtest.

Check that you have USB legacy support disabled in your BIOS setup. Some BIOS’s had a bug in them which causes memtest to write over the memory area used by the USB legacy support resulting in freezes or reboots.

- If memtest86+ shows no errors does that mean my memory is not defective?

Of course no answers are definitive, no matter how good memtest86+ will eventually become there is always the possibility that a particular type of error will go unnoticed. As long as you are having no problems with the system it will be pretty safe to say that the modules are good. If you are having problems with the system however you will just have to check by trial and error, IE; swapping the modules for new ones and/or testing with modules of a different brand/type.

- When I run install.bat it doesn't write anything to floppy.
You most likely have unpacked the memtest+-1.xx.floppy.zip file into a folder with a long pathname and/or containing + and - signs. It seems rawrite doesn't like that. Just move the files you unpacked to a directory like cmemtest and execute it from there.
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  #17  
Old 29-April-2007, 18:11
Austin_KW
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Default Re: PC Keeps Rebooting

Depends on what the options are set as. I did one yesterday that took about 2 hours to test 1Gb. Just watch the pass count as it may be set to do multiple passes.

After 4 hours, the RAM is probably OK. Gross problems are usually found pretty early with walking 1's and walking 0's, addressing and bank testing. There is just so many combinations but it is diminishing returns.
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Old 29-April-2007, 18:38
everton66 everton66 is offline
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Default Re: PC Keeps Rebooting

I stopped the test and booted up. It booted up OK. Now when I type in a URL and hit enter, I here some strange noises coming from inside the PC. Also the PC has cyber patrol on it cyber patrol is preventing access to ANY site with a mesage that "time tampering has occurred"?

No idea what this is.
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Old 29-April-2007, 18:54
Austin_KW
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Default Re: PC Keeps Rebooting

Clock changed or cmos reset or rt clock/cmos battery.
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  #20  
Old 29-April-2007, 18:56
Austin_KW
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Default Re: PC Keeps Rebooting

What sort of noise. Fans or clicking. Clicking means your disk is about to go to hard drive heaven.
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Old 29-April-2007, 19:04
everton66 everton66 is offline
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Default Re: PC Keeps Rebooting

No clicking however it has started rebooting again. I booted using a Damn Small Linux CD. I dont know anything about Linux and didnt know how to "drive it". however the PC did stay on and didnt reboot. When I took the CD out and did a "normal" reboot, it started to reboot again on its own. This would suggest it is not RAM or PSU? perhaps a reinstall of Windows is required?
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  #22  
Old 29-April-2007, 19:15
everton66 everton66 is offline
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Default Re: PC Keeps Rebooting

Doesnt reboot when I start in safe mode.
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  #23  
Old 29-April-2007, 19:23
Austin_KW
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Default Re: PC Keeps Rebooting

Any recent installs, maybe try a system restore to an earlier date.
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  #24  
Old 29-April-2007, 19:50
everton66 everton66 is offline
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Default Re: PC Keeps Rebooting

Tried a restore. I am reinstalling Windows at the moment. Thanks for your help so far.
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  #25  
Old 29-April-2007, 20:31
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Default Re: PC Keeps Rebooting

memtest I normally leave overnight to be sure but generally issues tend to show up within a few hours (or less)

Sil
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  #26  
Old 30-April-2007, 09:41
everton66 everton66 is offline
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Default Re: PC Keeps Rebooting

Here is the current situation:-

1. Rebooting only happens when Windows is started in normal mode

2. It doesn't reboot if Windows is started in Safe mode or when I used damn small linux

3. Memtest has been running for 12 hours with no errors found

4. Started to get a blue screen of death with "irql not less or equal" - searches on this suggest a ram issue - see number 3 above.

5. Tried to repair the Windows installation but still kept rebooting after completion
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Old 30-April-2007, 11:13
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centaur centaur is offline
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Default Re: PC Keeps Rebooting

This is an interesting, if frustrating situation. Since the 'puter will both boot and stay on without rebooting in both safe mode and via Linux, it would suggest a problem with a driver for something not contained in the slimmed-down 'safe mode' applications, or possibly a rogue or conflicting application.

have you tried using all the various bits of hardware etc and did any of them refuse to work or cause errors ?

I would have thought that a complete reformat and reinstall ought to clear this.
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  #28  
Old 30-April-2007, 13:45
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Default Re: PC Keeps Rebooting

You spend ages trying to avoid the old windows solution #1 "format and reinstall" but maybe it a has come down to it.

The only other thing is to add symbols and debugger and analyse the crash dump. A couple of commands might give you the driver that is causing this. I would do it just out of curosity, there is just a couple of steps and you don't need software training to make sense of it. A quick google gives this small tutorial http://www.networkworld.com/news/200...ows-crash.html.
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Old 30-April-2007, 14:22
everton66 everton66 is offline
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Default Re: PC Keeps Rebooting

Looks like it is going to have to be a reformat and reinstall. I tried the debugger option but XP wont let me install it in Safe mode and I can't access "normal" mode because of the problem - you think they would know that might happen, wouldn't you, and give a workaround....... but then things would be simple and we can't be having that.
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Old 30-April-2007, 14:48
Austin_KW
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Default Re: PC Keeps Rebooting

I can't remember how much info is in the small memory dump. I am not even sure anymore if it is created by default. It may contain enough symbols to allow you to copy it to another PC and run the debugger on the host PC. Most of my crash dump analysis/kernel debugging was done on proprietary OSs so I am a bit out of date. In principle it should work, but depends on how many shortcuts MS takes with the user mode debugger.
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