I, like most responders, live with this issue and think at some point that I could take the $100/mo that I'm paying Dish and just buy the TV shows from Hulu or iTunes. That way, we'd be guaranteed that we would catch every line of dialog instead of seeing Castle and Becket get all 'Minecrafted' while the key line of dialog from this week's episode is delivered.
I see this on playback on my ViP211 with EHD. My theory was it was being caused by the EPG download at the top and bottom of the hour. It seems to happen the most with OTA recordings (and since our ABC affiliate is running on a Low-power ATSC license, I thought that was the bigger issue) I wondered if there was something about the ATSC tuner in my 211. Since I'm not alone (and in good company!) I will muddle on and hope that Dish fixes it some day.