While watching our television, a black box will appear on the screen. We do not know what causes this. It is very intermittent. Sometimes we can watch all evening with no black box. Sometimes for just a few minutes and the black box appears. Has anyone else had this problem and how do we make this stop happening?
Steve,
What I think you are seeing is Letterboxing and it is normal.
Here's a link and an excerpt to a Wikipedia article on it:
"Letterboxing is the practice of transferring widescreen film to video formats while preserving the film's original aspect ratio. Since the video display often has a square aspect ratio, the resulting videographic image has mattes (black bars) above and below it; LTBX is the identifying acronym for films and images so formatted."
In short, your TV is wide-screen in format with an aspect ratio if 16 units wide by 9 units tall - long rectangle. The format for what was standard television aspect ratio was 4 units wide by 3 units tall - almost square.
When you are watching a channel that is broadcasting some content in a wide-screen format, it will usually fill the screen. When they cut to a commercial or another show that was created in a standard format, you will usually see a black bar (matting) on the sides of the screen.
Hope this is what your issue is as it is a "non-problem". If not, please give us more information and we will take another stab at it.