Mitsubishi rear projection vertical line problem

hello,

I've got a Mitsubishi 42" Rear Projection television. Its about 2.5
years old, and I haven't had any problems until recently. Lately,
every once in awhile, I notice a vertical line in the center of the
screen, when there are constrasting colors. For example, in the
background there were a set of bright blue blinds over a window. A
man's head was in front of it. The line was over the man's face and
was the same color blue as the blinds. I have a 3 year warranty and
I'm going to use it, but I need to be armed with a response when they
try to tell me its the signal and not hte TV.

Any ideas of what this is???

Thanks!!!
Steve

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