Or corrupt video memory.

My guess is your video card is either extremely dusty (causing shortcircuiting here and there) or has seen its better days.

Is your pc located in a room that's dusty (with lots of carpets) or has a high temperature? Is your pc case ventilated enough? Is it standing in an open place where it can 'breathe', or is it placed smack up against a wall with no air-circulation?

I'd say, try to clean your pc (especially your video card), move your pc to a cooler, dust-free location, install a case with decent airflow (and preferably and extra fan or two), and try again.

If that still doesn't work, then your video-card is most likely broken. To be sure, try to get your hands on another video-card to test with. If that one doesn't have any problems, then we know the cause, and you can start saving up for a new one wink

"The Large Print giveth, and the Small Print taketh away" - Tom Waits