Audio drop-outs on playing from PVR

I have the 500 GB PVR.
Since about a month ago, I've been experiencing audio drop-outs when playing previously recorded shows. The audio goes silent for one or two seconds. When I do the 7-sec rewind, it plays fine until the next one, which could be 5 minutes later.

Tech support tells me that I can try the disaster recovery process, or they'll send a tech who'll probably replace the PVR. Problem is, in either case, we lose all recordings.

Any bright ideas?

Dave S.