Windows Media Player/CD Player

I am not sure how to explain this, but I have several computers all running Win2k Pro with all the current service packs. One a couple of the computers (networked work location) I can only listen to CD’s via Windows Media Player. One my two home computers, I can only listen to CD’s via Windows CD player. They look like they are playing in MP, but no sound comes out. I am stumped. Any ideas anyone? Thank You.