I have a PE8720 that I purchased and installed 30 days ago. Last week the display began to show black vertical lines approximately 1/2" thick and spaced every 4" (my screen is 106"). I have disconnected the video source, unplug the projector for 24 hours then powered the unit up. When the display was illuminated (at start up) the lines are still there. I have emailed BenQ and contacted my dealer today but have not heard anything yet. Does anyone have any thoughts? Has anyone experienced this? Any help would be appreciated. Thanks, Eric