I get audio dropout even when using my TV tuner, so it may have nothing to do with your VIP622. I split the antenna cable behind the TV so I can connect to both the VIP622 and the TV. Works great when recording an OTA channel and I want to watch another OTA channel. I am dismayed by the lack of maturity in HD as demonstrated by audio drops, switching to SD and back, etc. You'd think most of these problems would have been fixed over the past 5 years or so.
Have noticed the same, particularly on Chicago channel 2, which I know is weak out in the burbs.....but had a Heroes last week with no audio and that's a different channel... did a full reboot and rescanned locals, but audio still drops out now and then between the satellite channel and the same two ota's ...it's obviously also on the recording playback so I know it's not my 5.1 optical connection to my HK receiver