I have the same problem, although the reason is very likely to be GPU overheating, because I opened my case and the heatsink on the video card is, well, way too hot to touch. By the way, I use NVIDIA GeForce 8800GT.
I'm using the "powerpack" driver from NVIDIA's website, which is 177.83. There is a newer driver 177.92 there and I'm downloading it. I'm also downloading nTune in order to check the GPU temperature. Does your laptop happen to have NVIDIA's GPU too?