I've had my phone about a month exactly and love it, had no problems at all. All of a sudden this afternoon, I can't use the "slide to unlock" button to get into the front page, then can't click on any of the four bottom buttons. I've tried everything, re-booting, re-installing the latest update, everything. Has this happened to anyone else. I think I'm going to have to exchange it tomorrow unless someone has a remedy. Please help!