My mid 2011 27" iMac goes into the Apple store today. Seems it could not handle the game guildwars 2. Whilst gaming yesterday the computer froze up in a pink and yellow vertical lined screen. Now anything graphics intensive including watching a dvd kills the screen, makes it go different coloured lines, and makes the computer unresponsive (if for example I'm watching a film, I can hear it still playing in the background). I must then power off computer, sometimes power button works, other times I simply have to use mains plug! Before the freeze sometimes the screen breaks up as I have seen previously when a graphics card went on a past PC. I didn't expect such a problem with the iMac. I have the 2GB HD 6970M and thought it would handle gaming okay. Hopefully Apple care fix/replace it with no further issues. Has anyone else had problems through gaming on an iMac? I know it's possible it was a weak gfx card and just my luck. Or that something else is wrong. We shall see.