Mac Pro, volume stuck on mute.

I have a late 2006 Mac Pro 3Ghz dual. Recently the volume dropped down to nothing and when I access the control panel, I see the mute button checked on all outputs except the digital (the one I have never used). All inputs are also muted and I cannot uncheck any of them. The little volume indicator is sitting in the lower middle of my screen and won't go away.

I have tried:
Zapping PRAM
repairing permissions
trashing the sound pref
using a different account
multiple restarts and shut downs
unplugged and re-plugged both the headphones and line out

....and none of it has worked. The sound indicator shows up with the startup screen and never goes away...and I have no sound. If I drag the volume slider up, it just goes back down. Very frustrating.

I am guessing this is a failing motherboard, being that I have lost my "A" RAM slot, but I really hope not. This is going to be unbearable to live with.

Does anyone here have any other ideas? I have thrown in the towel (which I rarely do).

Thanks!

hey, at least the comp cannot hear the profanities directed it's way.

psychometry said:

Don't know how to fix it, but it would be cheaper to add a PCI sound card than a new motherboard.

Click to expand...

Ok, I could live with that, but does a PCI sound card preempt all the onboard sound stuff automatically? Would it put this problem in the background or is there a chance this deeper in the system than that?

666sheep said:

Reset SMC: http://macosx.com/forums/howto-faqs/302002-reset-system-management-controller-smc.html

Click to expand...

OK, Just tried the SMC reset ... no luck. Before the login screen even popped up there it was, zero volume.

Thanks for the try though!

Ohhh, and nothing is resting on the keyboard buttons. I have even unplugged the keyboard and had no change in condition.

Sharangad said:

If you go to audio MIDI utility can you change the output to the analogue out?

Click to expand...

Changing the output is not the problem, I can do that in the sys prefs. The problem is that no matter what output I choose ... it is muted.

Honestly, I could live without having sound as it appears this Mac is dying a slow death. It's the sound indicator on the screen that drives me bonkers.

SmilesLots said:

Run the combo updater for your OS. Often solves this kind of problem, which could be a bad sector on the HD.

Click to expand...

OK, so yesterday, just out of the blue while I was typing an email, the sound started working again. The screen indicator disappeared and I could raise the volume again....woot!

So, I followed your advice and installed the combo updater, the sound stayed working. Thought I had it nailed.

Then, this morning, I woke it from sleep and 30 seconds later, the sound dropped out and the issue returned. So, back to square one, no clue what caused it to self-fix and no clue why it relapsed.

grrrrrrrrr

netkas said:

most likely it's some hardware failure.

Click to expand...

That's what I was afraid of. Are you thinking motherboard or drive? and is there any way to test?