I have a LG plasma T.V., model 42PB4D. Black box/middle of screen

Turn off close caption in tv, need to go to menu to turn off close caption function, that will solve your black rectangular box problem.

Look for bad stk's on convergence module. This may take care of pincushion too.

THanks

get in ti the menu and turn off the TEXT option.

Your screen may have either burnt out or became disconnected somehow. Sometimes, it's as simple as a connector coming loose from its port; other times, however, there's physical damage to the wires/connector/port. I'd contact the manufacturer to troubleshoot it as far as it can go on the phone. I assume that they'll either figure it out right there, or follow their protocols and (assuming it's covered in the warranty) have you send it to them for diagnostic steps. The other alternative is to simply call a professional.

Y sus board issues

go into the menu and look at the closed caption option----if TEXT is highlighted--this is your problem---select CC! or if it has it OFF.The TEXT will only appear on certain channels and it most likely was activated by someone changing the closed caption options. If this has been helpful give me a vote to let me know.

Try turning off Closed Caption.

It sounds like your tv is in text mode for the captions. Try going into the menu, and go into captions, and set it to off. That should solve the problem. If not, do U have a cable box? If U do, try the same approach with the cable box B4 concluding it's something wrong with the tv.

You could have a couple of different things causing your troubles.
1.) it could be a bad panel itself and that would need to be replaced $$$$
2.) it could have a bad connection on the address assembly or the address board is bad. Can be repaired.$$
3.) could be a digital Video board that feeds the adddress board gone bad. $$

press caption on remote