I am getting this problem. I have a GeForce GTX 285 and Windows 7 Home Premium. For the last two weeks the screen flickers after about five minutes of inactivity, then when I move the cursor it flickers and then the display driver crashes.
If I leave the computer for any length of time I come back to find it has rebooted to the BIOS screen. This must be a problem with the driver, not with the hardware because my PC is not overclocked and it has only started recently.