Ok, so every now and then - more often recently - everything media on my computer will stop working.

Youtube/any streaming media - Videos will pause - I'll hit play, itll play wth no sound for about 2 seconds and stop.
iTunes - I'll hit play, the icon will change, but the seek bar won't move, the timecode won't change and no audio will come out.
Logic - Hit play and the cursor bar won't move, timecode won't change.

The only way to get it back is to reboot.

2.8gig core 2 Intel iMac, however this used to happen back on Windows XP.