I was using my iMac today and noticed the screen seemed to flicker. I shut it down and left it for a couple of hours. When I turned it back on, the screen was really flickering. It looked as though it was divided into thirds horizontally. The top and botton thirds were flickering and garbled. The middle third was ok. I managed to log back in and restarted it again. It them seemed to clear. It's ok at the moment. Has anyone had this problem before? I would think its either a dodgy panel or something up with the GPU? I've had it for nearly two months and not had this problem before. I guess if it continues then I should return it to the Apple store for them to have a look at it.