Ok, the other night i turned my computer on like normal and it starts doing this. After i have it on for about 25-30 mins i will hear something inside my computer cut off, kinda like when i shut my computer down just a little quieter. Then a couple seconds later my screen will change into a bunch of blocks and different colored shapes but i can still see where stuff was on my screen and can move my coursor around which turns into a block as well. If someone could tell me whats going on id appreciate it Thanks... O and here is what i have in my computer if that helps.
Video card-Radeon 9800 pro
memory-896mb
MotherBoard-Asus P4P800 SE
Video card-Radeon 9800 pro
memory-896mb
MotherBoard-Asus P4P800 SE