I just got HD capability with Cox Cable, Motorola DCT6412 III box, Mitsubishi WS-65517 TV, HDMI cable between box and TV.
While I am having some issues with signal strength, even when the signal produces a glitch-free picture, there is some "jerky-ness" to the motion, while watching the HD channels, particularly noticable on camera pans or scrolling titles, but also noticable to a degree on all images, it is almost as if there is every three or four seconds a frame lost and the previous frame is replicated to "fill in the gap". A hesitation, if you will, of the fluid motion of the scene. This effect is visible on programming from tape and from film, not a "film" issue.
Do you suppose this is also related to the signal strength of my cable feed? Or should I suspect it is something else? My TV shows it is displaying a 1080i standard image.