Screen is has a black box on it

If you wish to get some details; visit the site linked here. Pull up older posts. http://electronicshelponline.blogspot.com/ Line faults & possible causes to LCD & Plasma screen are given with illustrations. You can get an idea about the fault to an extent. Faults to all LCD & Plasma screen are similar, irrespective of its brand and screen size.
Search the site by type in the "BRAND NAME" of your device; (Exclude the model number), in the "Search box at the top right of the display window of the Homepage" to get gathered related posts

Most cable boxes have a cable connection for standard antenna on older TV. Best suggestion would be to ask your cable company

If you wish to get some details; check the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/
Line faults & possible causes to LCD & Plasma screen are given with illustrations. You can get an idea about the fault to an extent. Faults to all LCD & Plasma screen are similar, irrespective of its brand and screen size.
Search the site by type in the "BRAND NAME" of your device; (Exclude the model number), in the "Search box at the top right of the display window of the Homepage" to get gathered related posts

If you wish to get some details; check the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/
Line faults & possible causes to LCD & Plasma screen are given with illustrations. You can get an idea about the fault to an extent. Faults to all LCD & Plasma screen are similar, irrespective of its brand and screen size.
Search the site by type in the "BRAND NAME" of your device; (Exclude the model number), in the "Search box at the top right of the display window of the Homepage" to get gathered related posts

Check and replace its tuner. If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience. http://electronicshelponline.blogspot.com/

Do you have a "cable-box" that feeds your TV?

Some older cable-boxes cannot decode the newer 'MPEG4' (compressed video) video that some cable-companies use for some of the channels. So, you get "black-screen", since the audio-stream is NOT compressed.

Talk to your cable-company, to upgrade to the newest cable-box.

Look in set menu for close captions---there will also be a feature called TEXT---it puts a black box on screen----also some cable boxes have same feature and can do same thing.

Vertical output IC has failed. It should be replaced. You haven't given the brand name and model number here. I assume that it is a Toshiba TV. If so, Visit this site for more details. Type in the site name "Electro-help" either Google or Yahoo search box [not in the address bar of your browser], and click search. It is an electronic equipments service help site. All details you want are there. Note the position of hyphen in between words in site name, when you type it in. The site will appear as it is in web; subtitled as service help to electronic home entertainement equipments.

Pull up older posts. You can gather all details. Sometimes, clicking on the ads by the side and bottom of each post might give you more details.

Pull up older posts.

It sounds like closed caption is turned on in the text mode, go to the menu and turn off closed caption.

I HAVE THE SAME PROBLEM WITH MY SANYO TV THE CABLE GUY TOLD ME HE HAD AN OLDER SANYO TV TO THAT DID THE SAME THING AND HE TOLD ME WHEN THE BOX APPEARS JUST HIT THE VOL + OR - BUTTON AND IT WORKS ALTHOUGH ITS A PAIN IN THE YOU KNOW WHAT WONDER WALMART HAD A BIG SALE ON MY TV.

TAMMY