John, what it does is that the screen freezes... If I lock it, when I press the home button for the SLIDE TO UNLOCK to appear, it freezes. Sometimes it just stays black, and sometimes the screen turns on to the SLIDE TO UNLOCK part, but it doesn't do anything. You know that when you are in a call the screen turns off? It freezes there to. And when it freezes, I have to do a hard shut down (HOME AND ON/OFF BUTTON) and sometimes it doesn't stays in the Apple Logo with the INFINITE LOOP, and I have t hard shut down again... I can't use it!
This sounds like the same problem i went through, only when i installed a dumb program called Dock app which has a small sunburst at the bottom right. and all i did was Follow these instructions and it might work.