For the past week or so, I've been getting this bizarre problem with my video signal. I'll be using my computer just like normal, and all of a sudden it will look all garbled, like the attached picture. It looks like this until I restart. Here are the basic facts:

- this appears to happen randomly. each time I start my computer up it happens at a different time, and sometimes it doesn't happen at all.
- somehow, I was able to capture that image as a print screen. I'm not sure what that indicates
- I can still use my computer normally. Everything runs fine, I just can't see what's going on very well
- A while ago, this happened when I was in the middle of a game of GTA San Andreas. it happend several times. I could still play the game, but I couldn't see anything.
- I would blame the video card overheating, but I've got one these on it, and it never gets very warm when this happens.

Any ideas?