blacked out box on tv screen

we have have an older magnavox (i think about 10 yrs. old) that we keep in the kitchen.. it has the most annoying habit and always has. every so often the picture blacks out, not the whole screen, just the middle. there is still about a 2" strip of screen showing all the way around. last year a friend was visiting and he called a tv guy he knew and that guy knew what it was. no one wrote down how to fix it, it's apparently something with the programming and i would really like to correct it. anyone out there know what i'm talking about? thanks, debi