Solved the problem. You have to update your audio drivers. This may be more complicated than you think, because Windows Update didn't do it automatically for me.
I have an nForce2 motherboard, so I had to:
- Go to nvidia.com
- Click on Download Drivers
- Click on Platform > Audio Driver...
Hey guys, I'm getting that same restart after a half hour problem, too. Really annoying. Any ideas or workarounds?
All I know is that Windows gave me this link after it booted up again: http://support.microsoft.com/?kbid=293078
Hope that helps.