Unfortunately, it's difficult to determine what the problem could be. It could be the board inside of the television, or the television panel itself. Without being able to actually inspect the unit, is difficult to determine what problem could be. Your best bet is to call 800-SAMSUNG to have your unit inspected. If you haven't purchased an additional warranty at the time you purchased your television, it may be an out of pocket expense.
I have a 50" Plasma TV which is about 2-3 years old. All of a suddent the top half of the picture goes black. Stays that way for a while then goes back to normal. Some times I have to turn off the TV to get it back to it's normal picture. Is this TV shot? I may be out of warranty and wonder what is wrong. Is this repairable? Picture is great other than this issue. Any help would be greatly appreciated.