lost audio on two channels

I have a Dish 722 DVR and a 622 DVR in different rooms. Both have Dish HD content *and* off the air digital HD channels from the same sources using exactly the same cable setup splitters and muxers. The whole thing worked after initial setup. On the 622 which feeds a Denon AVR4302 and a Sony Rear projection TV with fiber optic digital audio and composite video it still works. On the 722 which is feeding a Denon AVR2809Ci and a Samsung LV40A750 over HDMI all around I've lost sound on only HD ch 4-00 and over the air digital ch 4-01. this affects DVR recordings from these channels as well. I do have audio from reg def 4-00 and over the air digital 4-02. I also get audio when I switch to the over the air digital antenna input connected directly to the TV and as I said, all these channels have audio from the 622.

So to recap the system with the missing audio is a 722 with HDMI cables.

Called Dish and they've opened a bug-report and will be checking their software. I've reset the 722 a couple times. I've power cycled everything. I've checked the HDMI cable and reseated it. The cables are high quality cables from blue jean cable and since the audio works on the other HD channels in the 722, it doesn't "feel" like a bad cable.

One additional piece of info, when watching a DVR'd episode of Life from Dish HD Ch 4, every time the signal changed from full HD to something less like in a commercial or when they ran the powerball banner below the recording lost sound. As soon as the picture returned to full HD the sound came back. But, now watching live HD I get no sound regardless of the picture content :(

Any ideas would be appreciated

id say its dish. in the last two weeks i have lost sound on two different programs for 1/2 hour or so. the program started out with the music and some sound effects but no voices. it was kinda weird. i could hear the programs music but when they talked nothing. after about 20 minutes the picture went to letter box and then voices.

Sounds like it was a sound mixing problem at the station. No center channel. I've seen (heard) it before.

Latest info:
Bought an optical cable and wired the Dish 722 to the Denon AVR2809Ci with both optical digital *and* analog as well as swapping the HDMI cables. If it was an HDMI issue changing the audio input method from "Auto" to "Digital" on the 2809 should have fixed it -- alas no joy. Changing to analog does get audio! forcing analog also provides sound on the DVR recording that have no sound when using the digital inputs. So it seems that it has something to do with the digital audio processing.

Then I took the 2809 completely out of the loop and took the HDMI directly to the Samsung TV. Guess what? Audio worked perfectly!!

So it's still something to do with digital audio processing, but not the Dish 722, but the Denon 2809. When receiving a full HD signal with associated high quality digital audio I get sound, but on moct commercials and when the picture is shrunk to make room for a weather advisory or PowerBall announcements I loose sound. So it "feels" like a translation issue -- the receiver is expecting audio in one format, and it must be getting it in an incompatible format.

Since this did work when the system was first set up. My next step will be to reboot/reset the Denon and start the configuration over from the ground up.