Possible codec issue?

I have been fighting with my desktop because it has been recently having annoying audio glitches

For a while it would regularly, about every two minutes maybe, mute for about a fifth of a second, and make a low feedback sound. It did it to speakers and a separate mic in. Now, that hasn’t happened in a while, but now audio does a strange fade-out then back in. I can’t figure out what could be causing the problem. I can get to the sounds–>properties–>hardware–>audio codecs and look at the list, but I have no idea if there are any conflicting audio codecs there or not.

Any other ideas on what could be the problem? I re-installed directX just on the off chance that would help, but nope.

I’d appreciate any help getting the ol’ system back into crystal clear audio.