macbook loses sound

I am wondering if anyone has had any problems with their macbook losing sound. It has happened to me twice now and I am clueless thus far. When I try to turn the volume up or down, I get the volume box which shows all volume bars, but with the muted circle. I try to play any videos or songs in itunes and I get nothing. Plug in headphones, nothing.

The first time it happened, I had to re-install/reformat the hard drive, and everything was fine. Interestingly enough, when I attempted the install, it always failed until I removed the aftermarket memory I had installed. I guess it is possible this memory could be the source of the audio driver problem?

Any help or advice is appreciated. Also, just prior to this happening, Safari kept doing the "unexpected quit" thing, and kept indicating a kern failure/bad access failure.

Thanks.

Hi,

it sounds as though I have been having a similar problem to you. I havn't fixed it yet but I can tell you what's been happening and what I've tried.

2 days ago my macbook randomly just stopped producing sound. The volume bar at the top of the screen had gone. When I tried to change the volume using the keyboard, the symbol was coming up on the screen but only 2 /3 seconds after I was pressing the button (like it was crashing or slow) and the ticker wasn't moving up or down and no sound. Then suddenly when I used the keyboard buttons a moment later the sound symbol came up instantly but this time with a line going through a circle underneath it to indicate no device.

Under system preferences, Sound, it stated that no output decvices found, so my internal speakers are not being recognised. Plugging in externals or earphones makes no difference still no device recognition and no sound.

Ok so I looked about on the forums to find a fix. I found something that said I should try going into HD, Library, Preferences, and then deleting the file com.apple.audio.DeviceSettings.plist (this file will automatically regenerate) and restart.
Did this and upon restart at first I got a black screen (no grey screen)..so I hit the power button off and on again and this time I got the grey screen the startup sound and then sound was working fine again. sorted i thought.

Used my macbook that night (sound all fine) and then left it on but closed the lid for it to sleep overnight.

Next day open it and sound isnt working again.
Spend ages turning off and on and off and on, rebooting the PRAM, deleting that file agaiN. None of this worked so then I searched for updates on the apple website and installed the latest update and the combo update and this didnt works so finally totally re-installed OS X from my discs.

Still no sound.

Spoke to apple support, who think the prob is hardware related (I really don't) and I'm going to the apple store tomorrow.
However, switched it on this morning and I got the sound on startup - this hasn't been working for a whole day. However when my desktop came up the sound bar was still missing and all the same prob still persists.
Tried rebooting, but start up sound has gone again too now.

I'm convinced that this is due to some sort of software problem, maybe due to the automatic update of some other program.. it seems strange that the sound initally went and then came back and then went again and then the start-up sound came back and now gone again..
Oh and when I open garageband I get the error message;
Core Audio - Selected Driver not found. (-10202)

Anyone with any suggestion or help would be much appreciated.

Cheers

ARGH!!! Me too... I just registerred on this forum because I didn't know where else to turn. I hope it's something simple. I bought a mac because they are easy for non-computer folk to understand. I don't want this to turn into a huge problem for me. The weird thing is, when I plug in my headphones, the sound does work.