No sound

Hi,

I have a Imac running Lion 10.7.4 I am pretty sure since I upgraded to the latest version, about 2 weeks ago, I keep losing all sound. If I restart the computer it all returns but over a period of time somewhere I just lose the sound. Preferences show everything ok, Internal speakers, not on mute. I usually put the mac to sleep when finished, rather than shut it down.

I have tried to keep track of the applications I use to see if one is causing it but nothing.

Any help please.

Clearly not much help in this forum lol

losing sound

I too have recently begun to experience sound loss. I play a casino game on Facebook and within 2-3 minutes of playing, the sound slowly starts to go. If I go back to FB page and then back to the game, the sound is ok, for another 2-3 minutes. I don't lose complete sound, but it might as well be. I'll open another tab and play a video on Youtube, no sound. Had no other issues before this, and have not changed any settings. Anyone advise?
Thx!

Well don't hold your breath for help Junie