I have a Scientific Atlanta (Explorer 8300 HDC) cable TV box. When watching TV, I find that a large, black square will appear in the center of the screen, covering most of the picture. I had found that pushing the "mute" button on the remote will cause the black square to disappear. It is now happening more frequently and is very annoying. Is the problem my cable box?
Sounds like the Closed Caption somehow got turned on with the TV. If you have the remote control for the TV itself try to go into the Menu and make sure Closed Caption is set to "off"