for giggles check your sound card itself to make sure it is seated properly. It could be little bit lose.
My Sound device is actually connected by USB. I've double checked to make sure the cable is connected okay.
I'm also considering another possibility. I had the sound cut out again on me, and it was at a time when a download was completing and the file was being saved. I think playing sound at the same time as the CPU is doing a lot of work overwhelms the system a bit.
Just a theory at this point.
Dave