I've been having the same exact problem with my HR20-700, and for about three weeks or so. Up until tonight it has been OTA recordings. Tonight however, I watched a D* recording from Monday and started getting split second sound drops, but not the freezes like I get on the OTA channels. I did a quick rewind each time, replayed the sound drop segment again and the problem was gone. This happened several times during the recording. I thought I'd come here first before calling D*. Has anyone found a solution to this since Jimbo's last post or 12-07, or determined what may be the problem?
I have not found an answer to this problem, however, others that have the problem are telling me that it's more than just the OTA channels.