I am assuming that you have a nvidia graphics card and a creative sound card. If I am correct so far then I would do two things.

1. Uninstall your sound card drivers

2. Make sure you have the latest drivers for your video installed.

3. Run your system without sound and see if you continue to get the same problem.

4. If all is going well, try installing latest drivers for your sound. If you then start running into the same problem after that then that is the problem. I dont know how to fix that, it would be a creative labs compatibility issue with vista.