On some of my HD channels, I get severe pixilation occasionally to the point the picture goes out completely. It stays out a few minutes with the message, "This channel should be available shortly." I've replaced the box twice, opened the wall plate up and all connections look secure and tight. I have 1 splitter hooked up and even replaced it, removed it, everything. Changed wires, don't know what else to do. Comcast wants 70.00 to come out and fix whatever the problem is. Is it a weak signal? I need help!! I'm tired of this crap. HELP!! Thanks, Andy..PS--SD doesn't do this at all other than on the locals