HELP!If I leave my phone locked for 10 mins it says phone locked please turn off -->

[siemensc60]

Please can anyone help or does andyone have the same problem with their phone? I ahve a siemensc60 and yesterday itstarted acting up , now everytime I leave my phone locked for 10 mins or over it says phone locked please turn off. I know its not bllocked because if I unlock it before the 10 mins are up I can send texts and its just normal. I also know that althouygh my sim card is fairly new it has nothingto do with that because I put my old sim in and it was no different. I now have a genie card and that is acting upaswell and its always on network search and not letting me send or recieve messages sometimes until hours later please can someone help !? Should I just sell my phone and get a new? If so which reliable phones are recommended? Thanks. xxx