.wav and .mp3 won't play - .mid just fine?

[dlk9s]

All of a sudden today, the sound is not working correctly on my computer (Windows XP, Creative Audigy 2). WAV and MP3 files won't play - can't hear Windows sounds, YouTube videos, etc. Mysteriously, though, midi files will play just fine.

I ran a diagnostic program and it says everything is fine, but obviously, it is not.

Any ideas? I tried system restore, but to no avail.

I may just reimage the computer tonight, but if I can find a solution before then, that would be fantastic.