My model CF32E50 has been displaying a large black rectangular box on the bottom half of my viewing area during my cable TV input from my Comcast Motorola cable box. Prior to this, there was only audio, then I unplugged the cable box and plugged it back in. Now there is is video, but with the box showing. There is no difference changing it from STD to IHC or HRC in the TV menu. The video is fine on our backup TV using the same cable input, and a DVD input is fine. I am not sure that the problem is, or where to go from here. This has an analog TV tuner converted through a digital Comcast tuner box. Thanks.