[dbump]

It wasn't the drivers--happened again. Also, I don't think it's anything but BTV. I have the WinTV2000 app from Hauppauge installed, and I can close out of BeyondTV--with no audio, open WinTV2000, hear audio fine, change the channel using my digital cable box remote, to verify that I am getting input from the same source, and then exit, go back to BeyondTV, and no audio there again. And, as before, an RCA audio out, coming from the cable box, has full audio. It's just BeyondTV that's ignoring the signal.

Time to open a support incident.