I was having this exact same problem. I was hoping someone had a reply for you but it looks like they didn't. Did you ever figure out what was causing this problem? I had the problem, it went away, and then another problem started occurring. The right side of the screen now is dark upon turning the tv on, then gets better and ok after about 15-20 minutes.
Anybody know what causes the above poster's issue and the following issue I have had?