I'm using the 8000HD, and I've had exactly the same problem with digital sound for a month. If I just use the analog cables, I don't have the problem. When I add the digital cable, I don't have sound about 30% of the time when I change channels on digital channels. There appears to be no problem on the analog channels. If I wait about 3 minutes, the sound will usually come on. Also, if I hit the "Volume up" button, I get the sound to come on. Another thing that happens is if I have the receiver on "Mute" on a digital channel, it will sometimes unmute by itself, even though the receiver still says "Mute". I have replaced thee 8000HD box, the receiver, and the cables....still have the problem. TW Cable has thoroughly checked their line, and it is fine. TW has a Pace HD box without DVR that I may try just to see if it is a Scientific Atlanta problem.