I have a c7 and For whatever reason the usb affects the touch screen response for example when i have it connected to my cpu if i move the usb connection one way it works but another way it doesnt.its really weird.Im not due for an upgrade with tmobile til may so I need this phone to work.The last thing i did was take it apart and cut a piece of a business card in between the usb port and the back of the phone.the touch began to work but Now the phone wont recodnize the sim card.So now Im lost.please help if anyone knows what to do let me know