Hi All, pardon the stupid questions, but I'm new here and I honestly tried searches and could not find the answer. Anyway, I just got COMCAST HDTV hooked up yesterday. I have a RPTV HD TV. When I watch a few of the HD channels, which look amazing I have to say, sometimes when there is a lot of movement in the video the picture becomes "pixelized", where I just see a bunch of tiny squares, like the kind you see when a digital video signal is losing strength. But then when the scene slows down, the pictures clear up and are super crisp again. What is this phenomenon and how can it be fixed? Many thanks!