I had the EXACT same problem as you. I sent my video card back to Creative Labs, and it's being repaired by them as we speak.
I had just bought a new monitor aswell so I assumed it had something to do with it, but I tested another monitor on my computer and it didn't solve the problem. I replaced the video card with a different one and it solved the problem.
I assumed the problem was related to temperature\heat because my fan was making strange noises and it looked like it was spinning at a slower rate than usual.
If I were I'd send it back to the company to get repaired.
*EDIT*
They may even replace it for me\you. I hope they tell me the video card is so screwed up that they have to give me a GF3
