Help with a graphics problem?

My girlfriend and I like to play WoW. Well she was doing a raid the other day, and since that raid her computer like bugs out. It's graphical we're sure, we just can't pinpoint exactly what it is. Every time she logs in the screen freezes and locks up the whole computer. She's got a notebook that came with a nVidia geforce go 7600 series. It worked fine before the raid but since then certain pixels freak out and lock up her computer. She installed the new drivers but they really didn't do anything. Just every time it locked up windows would manage to recover. We could use any help you can offer. She's running Windows Vista: Ultimate 64-bit.