Sober.
Have you upgraded your graphic card drivers lately or your main memory?
i've had similar results with both before with new drivers getting corrupted (removal of driver and going back to an earlier driver solved this) and i've also had the latency timings on the memory in the bios not working as described causing intermittent memory glitches which instead of the BSOD gave me a black screen.
__________________
 Yarrr!
|