I've had this monitor for about 7-8 month's now and have not had a problem with it until the other day. When I turned on my computer, a series of whitish lines appeared from about 2/3 of the way down the screen, running to the bottom. They faded in and out for a while and after a few minutes dissapeared completely without me making any adjustments to anything. It was almost like the monitor had to warm up or something. This has happened a few times since then and the lines have appeared in the same region. Any idea what the problem could be?