My friend just gave me her old Mac OSX 10.5.8. Everything is fine except there is no sound except at start-up and shut-down. I've tried using the internal speakers and 2 sets of external speakers to no avail. I've checked everything I could think of - all the speakers are turned all the way up, and everything I've checked says "this device is working properly." I've tried 2 CD's, Windows Media Player, Real Player, iTunes, and YouTube. I still can't hear anything. Does anyone have any suggestions? What am I doing wrong? I checked with the previous owner, and he says the sound was working fine. Thanks for your help.