My 36" Zenith PIP has a black box that is about half the size of the screen pop up from time to time and this box has white jibberish writing in it , If I change the channel the box goes away for a while then seems to return ...what is this and why is it popping up in my TV ?
Someone has turned on the text or the Closed Caption feature on the TV set. Im not sure on this set where the closed caption is controled, as there is no model number and I can not guess about this. Please if you need assistance at any time, I, or we will be more then happy to assist, but we cannot be fortune tellers and try to guess what type or model of set you have. If you cannot find the closed caption button on the remote or in the menu, Please get back to us and we will assist you in turning it off. Please let us know also how you made out with this set. Good luck
You can also see a description of this problem in this "Ask The Experts" article:
Ask The Experts: Why is There a Big Black Box On My Screen?