Have a Set that I need some help on. The 50" Plasma TH-50PX50U. This set when turned on has a great picture for about 15-20 Min and then I can see red and green dotted lines that look to be vertical. I can still see the picture but the lines are there to. I have used freeze on every thing I can think of to make sure nothing is getting to hot but that did not help. Any suggestions would be greatly appreciated. I can even post a pic if you think that would help... Thanx