Macbook Pro won't play any sound This was working earlier today, but suddenly didn't work when I tried to play music in iTunes.

I open iTunes, select a track, click play, the track doesn't play. The play button toggles between pause and play, but there is no sound and the position status bar does not move.

So I dropped a little lower level:

$ afplay audio.mp3 
2011-12-13 12:28:51.446 afplay[30725:903] AQMEIO_Base::DoStartIO: error -536870184
2011-12-13 12:28:51.519 afplay[30725:903] AQMEDevice::StartIO: error -536870184
Error: AudioQueueStart failed (0xe00002d8)
[exited with 1]


Tried restarting the coreaudio daemon.

$ sudo kill -9 `ps ax|grep 'coreaudio[a-z]' |awk '{print $1}'`


Still nothing.

Failing applications:


Quick Look in Finder
Quick Time
Youtube content in Google Chrome


It would seem to be either some low-level issue, or hardware? Any way I can confirm?
meh. A reboot fixed it. What is this, Windows? I would still like to know what caused the problem, what other avenues I should have explored and how to resolve it without rebooting.