Anyone ever have their plasma get pixelated when the walk near it?

Weird. Since it's only happening with one particular channel, then it's got to be something with the SA HD Box, not the TV. The TV doesn't know what channel it's on, it's just getting a signal from the cable box. What channel is it?

Maybe do an experiment - move the SA HD cable box several feet from the TV and see if the channel still gets pixelated when you get near the TV or if it only happens when you're near the cable box.

Is your cell phone in your pocket?

My droid can sometimes cause a hickup in the signal when sending and recieving text messages.

Yes, try changing the position. Sometimes with amplifiers that aren't properly designed, you get interference with your speakers depending on position. I would see if moving around the HD box to a different position could negate the interference you're getting.

Another question for the OP though... what do you mean by pixelation? Do you mean that weird blocky stuff or do you mean that you see individual pixels. Your set is 720 so seeing the individual pixels is entirely possible and inherent to the set... if it's just the cells of the display you're seeing. If you're seeing graphical glitches or artifacts then it's something improperly shielded somewhere in the chain.