I just bought a Sony Experia X10 and am trying to use it for the first time. I put in my SIM card and the phone went through the start up but it will not recognize that there is even a SIM card inserted. I used a friends SIM card and it didnt recognize that one either. I read something somewhere about having to shut of a task manager?? or something like that first. This is a used phone that worked just fine prior to me. What am I doing wrong??