I'm running Windows XP here, and experienced something similar recently. I discovered that my IDE optical drives were listed as SCSI devices in Windows Device Manager under "DVD/CD-Rom drives".
I tried removing the drives and rebooting to have Windows reinstall them, but no joy.
The fix for me was to reinstall my motherboard drivers.
It may well be completely unrelated, but the symptoms are the same. WMP could both rip and play audio discs while MC encountered problems.
-marko
