Welcome to the MacNN Forums! You can reinstall the drivers CD (you DID burn that CD, right?), and that should fix not only the audio but the rest of the Mac hardware that may not be working as well as it might. If you have already installed the drivers, reinstalling them won't hurt at all. You could also manually reinstall JUST the audio drivers, but finding the hardware under Device Manager can be a chore-it won't always tell you what the device is, just give you a yellow exclamation point and call it "Unknown Device." Because of this headache, I recommend reinstalling all of the drivers. It's just simpler.