If you read the T.V manual you'll see in the instructions for usage, that the TV should not be placed where it is exposed to sunlight. Your T.V maybe placed so that sunlight can directly fall over it, maybe near a window or door. You should either move it to some other place where it is not exposed to the sunlight even when the curtains are pulled back from the window. If the blue shadow disappears in a day or so after you move the T.V, you've already fixed the problem. If not, you may have to show it to a technician. The problem can be resolved by replacing certain parts, so you won't have to buy a new one. Good luck!