I just registered to add my experience to the mix
Yesterday morning I turned the TV on to catch my morning ESPN HD no audio I tried a couple of things and finnally rebooted the satelite reciever(622) and every thing went back to working
Got home turned on the TV no audio rebooted again and everything worked listened to sirius radio for an hour or so. when the wife got home I decided to record one program OTA and settled in to watch another program and then the sound went out again since I was recording I switched over to the OTA waited for it to go to commercial break and rebooted again. 15 min later the sound went out again I rewound? back to the part I had just watched with sound and still had no sound. Then I went into trouble-shoot mode some observations
No optical audio out on TV1, although light is still present
No RF audio out on TV1,I have a 622 and a 525 and I have it set up where any TV in the house can view any satelite tuner on channel 4,59,61 and 63 in this case channel 59 is TV1 and it did not have sound
The sound is fine on TV 2
programs recorded on TV1 (while the sound is not working)can be played back on TV2 with sound I did manage to finish watching what I was watching by recording the remainder of it and watching it on TV2 (which is Channel 61 at my house)
once I was done watching it I deleted and that caused the system to reboot
on the upside maybe I should just record 10-20 1 minute clips at least that way I won't have to get off the couch to fix the audio problem