Facing TV Problems? Ask a TV Technician.
Hi, I'm Pete. Welcome to JustAnswer! I'm reviewing your question now, and will post back with your reply ASAP.
This problem is caused by a faulty driver board.
Inside the TV, on the left side is the Y-SUS board there are two boards connected to it. The one on the top drives the top half of the picture and the one on the bottom drives the lower half of the picture. Check the ribbon cables to make sure they are securely connected.
If that does not fix the problem the the board itself is bad or possibly the plasma panel has a fault.