W200i keeps shutting down and reappear like crazy...?

the phone keeps shutting down..and reappear back and then hang when i wan to text message or sumthing....issit because virus infected my phone while i was trying to transfer stuff to my phone from my computer??? bcz i scan the memory card and it got infected by trojan crapp.....wat is wrong with it?? plz tell me wats wrong with it!!!! im so desperate