I'm having a similar issue
Sound just cuts out and it doesn't matter what program, for me.
Winamp cuts out with error, JetAudio cuts out with error, Skype cuts out and says "cannot communicate with sound card" and I have to call people back without closing skype, Dvds cut out as if they are skipping, and they come back.
Restart any of these programs and it's fine again.
Sometimes out of no where, the stereo - that is connected to speaker output - starts squealing really loud... turn it off and back on, it's fine.
I tried windows update 2 days ago... nothing changed.
It's like something is either loose or it's some driver
I have onboard sound by the way.
I'd love to get rid of this problem