Hi,
We had similar problem on our Panasonic TX-LZD800 after Sky HD box was installed. Upshot is after trying 3 different Sky boxes i.e. Amstrad, Samsung, Amstrad again, it was definitely better when using the Amstrad again. Oddly, with each box there seemed to be a slightly different problem, with the first box there was just a black line that went half way across bottom of screen; with Samsung box there were black and white lines at top of screen, which was quite bad, and with the third Amstrad box, we had black bars down side of screen, but at least it meant we didn't have to keep switching on the picture overscan, which we felt just magnified the picture too much. Switching the aspect didn't seem to make any difference with the bars. The upshot is it was checked by Panasonic delivery guy and he confirmed that it was a faulty TV. I posted a thread on here about 3-4 weeks ago re: Problem with Panasonic TX-LZD800 - anyone else?
paws