Large Black rectangle on bottom half of screen

My mother-in-law had this problem on a Quasar for two years before she finally mentioned it. The rectangle is a text box for closed captioning or for a demonstation list of features, but without the text. I restored the factory presets and poof... problem solved.

Look in the manual and find how to restore the factory settings - it will probably be some weird combination of buttons that you would never guess. On her set, which has a built-in VCR, it was simultaneously pressing "play" and "FF" (on the set, not the remote) for five seconds until the set powered down. Yours will probably be something different but equally odd. That should get rid of the black rectangle. Then you go through the initial setup and you're back in business.