I have an Onkyo TX SR504 recieving its sound from a Dish vip722 via optical output. Lately, every once in awhile, when you change the channel after browsing the guide, the sound will not come on with the channel you turn to. Usually it's that one channel, sometimes its all channels, and at other times its every other channel or so. The fix for it is to turn off the AV receiver for a few seconds then turn it back on - and voila! the sound is back. This is beginning to be frustrating. Anybody have an idea?