I got a good deal on a flat screen Samsung plasma tv. From day one if an image displayed for longer than one minute it would burn in. The burn in was never permanent but it persisted for a couple minutes (longer if the burn-in was black or white text). I thought this was a facet of the tv being plasma but then I spoke to three other people who have the same exact tv (well, theirs are a little bigger) and don't have the burn-in problem. Is this a defect with the tv or is it normal?