Panny Plasma Problem...
Sounds as if you might be well served by calling the Panasonic warranty service number, and explaining the problem to them. They usually have fairly well trained (or at least, well scripted) people on the phone who can help diagnose the problem. I have a 34" HD CRT with which I've had a couple of problems, and they were willing to listen and help, even after it was out of warranty.
Word of warning, call them when you have a lot of time to burn, because you'll probably wait on hold (at least it's a toll free #) for quite some time before you speak to a tech type person.
Let us know how it goes...
Pat