I have reported this to Dish Network (and call back every other day). They said it is not a known issue. My NY locals are NYC CBS and NBC. When I get a show that has no sound, it is for the entire show and vice-versa. If a 5.1 commercial comes on during a 2 chan show, it will not have sound and if a 2 chan commercial comes on during a5.1 show, it will have sound. Also when I switch to a non HD channel (even CBS or NBS) the sound is fine and my AV receiver switches to Dolby Pro Logic, so I know my receiver is doing what it should.