So today i couldn't boot my iBook, just won't boot. So i booted into safe mode, then restarted. worked fine, but then the screen went nuts, vertical lines moving really fast, and then it just went to a crazy pattern of the blurred desktop. i'm using it now, and it's working fine after a restart, but are there any prefs i could trash to try and fix this problem, it's happen a couple of times today???