Sound volume control unresponsive after waking from sleep

Question

Lately, a strange problem has developed on my MacBook 13-inch Aluminum (Late 2008), running Mac OS X 10.6.4:
After waking the MacBook from sleep, the sound volume control keys on the keyboard does not affect the volume control of:
* Neither the sound volume output by the built-in speakers,
* nor the sound volume indicator/slider in the menubar,
* nor the sound volume indicator/slider in the Sound preference pane in System Preferences,
Only the sound volume slider/indicator in the Sound preference pane in System Preferences has an effect on the actual volume ouput by the built-in speakers.
First I thought the problem was affected by disconnecting a set of analog headphones while the MacBook was sleeping -- it seemed that after sleep the volume control keys on the keyboard and menubar item still was set to affect the headphone port and not the built-in speakers.
However, the problem just occured after sleeping without anything connected to the MacBook. The built-in speakers were muted, when the MacBook lid was closed, and the computer went to sleep - after waking from sleep the built-in speakers were unmuted - and control was only possible through System Preferences.
Any ideas?

Answer 1

Not sure if you stumbled on the other threads like this one:
http://discussions.apple.com/thread.jspa?messageID=11801555&#11801555
I've been having the same problem on my Mac Pro for a while, finally decided to see if there were some other people having the problem. I'll see if the others have a solution yet.
One workaround I've been doing is to go to Preferences -> Sound and select a different output device. For me, I have to flick to Internal Speakers and then back to Line Out.
Brett