Thanks to many of the posters on "It is software" & "The necessity of 2 satellite inputs", I can on command make unwatchable recordings. Here is the setup: 2 HR-20s, one with 0120 & the other with 012a. Removing SAT 2 will give every other channel change the error 771 sat 2. It doesn't matter what channels [SD, HD, HD MPEG-4]. It is simply every other. If I repeat a channel change back to a channel with 771, I can get the channel if the previous was 771. Simply every other channel change with only one feed connected [in this case #1 on & #2 off, with BBC connected]. Now if I tune to channel 282 [from a 771 channel] I can record the program. Now with one tuner in use, when I go back to testing the every other channel: I get either 771 or a blank screen. If I press record on this channel, it records a blank screen. Both units are doing this right now. From the play list I see: animal channel recording and the other [one is local HD & the other is ES2H] is an "unwatchable" recording. I'm defining "unwatchable" as: a recording with the time line showing correctly, but no sound or video. You can't move forward, backward, skip, or anything. The boxes are completely responsive to remote control commands. If I were to RBR, these recordings would be removed from the play list. While I have "degraded" the units by "just" disconnecting SAT #2 & not rebooted the boxes, I believe this is how the unwatchable recording happen, or at least should help DirecTV to point them to the changes needed. We've got some very good members here & I never would have found this without their help.