Sound Quits Mid-Game

My Intel rig (see sig) has developed a new behavior. Randomly while gaming, i.e. anywhere from a few minutes to an hour or more, the sound will just quit. I am using the on-board sound. Sometimes when I escape back to the in-game menu, the sound will come back. Other times I have to get completely out of the game (back to the desktop) to get the sound back. What's up with that?!?!?

I have re-installed the AC97 drivers and have updated to the latest version. No joy. I don't think it's heat-related, as my system is running cool (28C case temp). The sound chip is driving an internally-amplified 5.1 surround speaker set.

Often times when overclocked, it will cause the on-board sound to drop. Try backing off on the overclock and see if that helps the problem