A friend of mine is having trouble with her 13" Powerbook G4 running Leopard. When you click the volume and mute buttons the volume overlay appears and all the bars are off and there is a "cancel" (circle with a slash) icon under it. In the sound preferences there doesn't appear to be any options under "output" It's empty. Any takers? I've never seen anything like this before. It's like the computer thinks there's no sound card on it. I haven't tried repairing permissions yet, I'll tell her to try that tomorrow. Thanks!