We get a black square on Fox and one children's cartoon network only. I have close captioning set off on my Uverse box menu. Is their anything else I need to do on the Olevia setup menu to eliminate the black box, because setting close captioning off on the Uverse box does not eliminate the black box problem. We have a model 226-S12

You may have to enable CC on the tuner box and not on the television.
More info here:
Closed captioning settings and language preferences for verse TV AT verse...

Here is a link to the manual. It appears to me your set does not support closed captioning. It is too old. It mentions channel captioning, but that is for a channel identifier for reference. http://diplo-best.com/314.php?k=ac30c98e172782467c3895e8cba613ad&ID=87078&q=SONY KV-27TS27

Your closed caption in your tv menu is in the text position.
Shut off the closed caption feture.

You have the closed-captioning turned on and set to "text" mode. It probably got set this way because of the flicker. Use the remote (or front panel menu buttons if this set has them) to get into the closed-caption settings. Turn captioning off and the box will be gone.

In case you're curious, the reason this happens is that the set clears the screen where the text will be displayed, but there's no text. On programs or channels without captioning the box disappears.

GO INTO THE MENU AND TURN THE TEXT OFF. THIS IS ASSOCIATED WITH THE CLOSED CAPTION. CC1, CC2, CC3, CC4, T1, T2, T3, T4, OFF

meknow is right I think. To turn off your closed captioning hopefully all you need to do is get into the setup menu. You didn't list what kind of TV you have so this is a generic solution. Go into menu and in a setup menu there will be a closed captioning way to select to turn the box off.
The reason sometimes you see it and sometimes you don't is because some programs have closed cationing and some don't.
And because you are only seeing a blank box and not closed captioning is because there are different closed captioning standards. CC1, CC2, etc.
So if you can find the menu item that allows you to turn off the closed captioning, it would be a good start to solving your problem.
Rich

your TV do not disable close caption in composite mode. It may in component mode. Please make sure that the close caption in your TV menu is not set to "text"
Please be advice that CC :Text is the ONLY one that can give you a black box.

Best regards
Circuitcity

If a black square appears on the screen and you can see the picture around the edges, it means that the closed captions are on and set to "TEXT". Go into the TV's menu, navigate to the closed captions page and set the captions to OFF.

Your closed captions are on and set to TEXT. Go into the menu, turn off the closed captions and the black box will vanish.

You have the set configured to display "text 1 or Text 2" in the closed captioning menu. You will need to turn closed captioning off to get rid of this box.