Sony Projection TV - Burn in or lamps? Something else?

[HRC]

Hey all.... I have a question. I have an older(5yrs) Sony projection TV that might be showing it's age of late. I receive over the air broadcasts from my HD tuner and most of the time.......the picture only fills the center part of the tv. Most of the time I have black bars on ALL the way around the picture. This varies depending on the aspect ratio of the station broadcasting. The problem is now when I watch bluray's with the 1:85 ratio or whichever it is that fills my entire tv screen......the part where my hd tuner normally displays it's picture is slightly darker. I can only see this on very bright(white/bright blue) scenes. Is this what is known as burn in?? Do I need a certian set of lamps? I just don't know if it's burn in or the lamps. Again, this is only noticeable during brightly lit scenes and is otherwise not noticeable at all. Is there a fix for this? Excuse my ignorance. I know the tv is old and down on quality and will be replaced when the time is right but for now.....it is bugging the shit out of me!!!