Hello. I have a 2003 Mits Diamond series 65" rptv. It has always worked great...until lsast week, when it went black screen with occassoonal flashes of a white horizontal line. Very rarely, it will function normally. I had an authorized mits repair guy look at it...but just my luck...it worked perfectly while he was here. He saw nothing wrong. When he left, the problem resurfaced, and I have no picture. I have hooked a dvd player to separate inputs on the tv but have the same issue...so I have ruled out bad cable wire and cable tv causes. Any thoughts? Much appreciated!