I do have a 24" iMac, bought in January 2007. But I have never had any problems (yellowing, color gradient, etc.) with the screen and I believe this is a graphics issue. I play WoW Mac-side and CoH Boot Camp-side. (My system software is still 10.4.11.) A few months ago I started to get weird artifacts in both games. I have made sure all drivers were updated and so forth. These artifacts include flickering, flashing of blank terrain, lines across the screen that look like the light graphics in CoH rave missions (if that makes any sense). This used to crash CoH pretty frequently until I uninstalled SP3 from Windows XP and now I just get the occasional graphics problem I described. They range from mild to forcing me to quit. When Windows used to crash after CoH, if I rebooted into Mac, I would have a strange, light square of color, sort of like a burn-in. If I used the mouse to select the area, it went back to normal as though erased. Recently I was playing in Firefox and one of those strange squares appeared at the top of the screen. Up till now I have had absolutely no graphical issues playing either game. Since the problems both started around the same time my best guess is a graphics card issue. In my iMac it is a 7600 GT. I don't know if it could be a heat issue as the fans never went on. I wager my first step is to open up the back and give it a compressed-air cleaning. If that doesn't solve it...is my video card hosed? I've also encountered slowing in Sims 2 where I didn't have it before. When not using graphics-intensive applications I normally have no problems, except for that color square in Firefox. Thanks for any help you can provide.