Hi everyone. I'm having the same sound problem, but it's recurring.
I've run NBI and rebooted and that fixes it. But only for a while. All of a sudden, I'll go to adjust the sound and it will be greyed out again. Once again, NBI+reboot fixes it, but I'm getting really sick of going through that whole 8-10 minute process all the time.
Anybody know of any way to fix this? Am I the only one this has happened to? I'm starting to wonder if I should just do a whole new OS install and start over from scratch, though I really don't want to do that.