I don't know. The reason I say it sounds like something in the optics is, "electronic shadows" are usually linear in shape and run on the trailing edges of images. They will show up on the right side of the screen from top to bottom. The fact that you have one that's left to right and top to bottom makes me think it might be something with the optics. Post a good picture of it. If the set is only 6 months old and under warranty, don't fool with it and call the same guy that did the first repair.
Sam, I don't know where you live but try this number 1 800 268 3404 and ask for Quammy he works for Toshiba. He's very knowledgable and helped me out with all my questions.