Looks like the main cause was the audio alerts. WHen i turn them on, the audio reverts to pcm and the beep comes up when a program is about to begin. If i turn it off, then the audio reverts to dolby 5.1. Among hd channels in network tv, I think NBC in NYC is the worst. Lots of macroblocking on top of the screen, especially with sports. AUdio can be hit or miss. For instance, dramas and shows on NBC have good volume, specifically the news shows which are the only ones in real 5.1 (Nightly News, Today, Meet the Press). CBS on the other hand played the derek jeter ford ad at a high volume than most ads during the giants-jets game last friday night. Everytime that commercial comes on in 2 channel stereo i turn down the volume!!!