Join Date: Jul 2009
Location: Halifax, Nova Scotia(Maestro whole home PVR with two terminals)
That is a really odd problem, Doppelganger399, and in your case, you might really want to check your HDMI cable. Although I don't watch SD channels much, I do flick to them once on a while, and I have never experienced your problem. I do use HDMI with my 3400.
Updated, after reading your post again, seeing that you tried several different cables as well as boxes. Now, I am really puzzled that this is happening to you, and makes me start to suspect your TV. (my TV is a Samsung, btw)