[Stecchino]

For no apparent reason, my iMac no longer outputs sound properly. Tiger does this every now and again and restarting usually cures it. Permissions are repaired automatically every day but I repaired them again and restarted. Now all I get is the volume change feedback, user interface sounds (like emptying trash), and iTunes. QuickTime movies do not output any sounds nor do any other apps like games, FireFox, nada.

I'm running 10.4.4 and the Sound preference panel indicates everything is operating just fine.

PROBLEM SOLVED: http://docs.info.apple.com/article.html?artnum=300832

[chrisutley]

I had a problem like this and a MacNN member gave me a great tip. Try launching Garage Band. When it starts up it apparently resets all sorts of audio stuff, and it fixed my problem along with a friends Mac so far.

[Stecchino]

I've solved the problem already (see original post). Thanks for the suggestion, though.