Weird problem with the demo

I just had a strange problem with the demo. I just have a nice new computer (dualcore), so I decided to retry the flight simulator x demo.
It ran damn fine with all settings on ultra, no problem....untill the demo time ran out.

I was just trying out some keys, and discovered that pressing q muted the ingame sound. But just as my sound gets muted the time runs out. So I close the demo and guess what, all my computersounds are still muted!
I check all my sliders in the windows sound options, and in my soundcard options, everything still set as usual, on full volume. All drivers are still intact, but not even static coming from my speakers. And I cant go back into the demo to unmute the sounds cause the time is up. A reboot wont help, even the trusty start up beep is gone.......
Only thing that fixed it was a system restore to the moment before I installed the demo. Go figure....