Hi all, I have a problem... the problem first occurred after installing modern warfare 2 on a Windows xp partition on my iMac. After opening the game and starting the first mission, a few seconds in the game suddenly colors start rolling in bars at the top of my screen. They go away sometimes for a few seconds and come back just the same as before. But it doesn't matter as the computer as already frozen and i have to reboot. After rebooting again in windows I restart the game in safe mode. Re- apply the resolution settings and start the game again. And the same thing happens again. The next day and figuring windows is to blame, I start up in lion and reformat the windows partition and install it again. After that I restart again in lion wanting to check for mail etc. and notice it takes longer than normal for my startup. No problem yet, it took a bit longer but it got there. I open mail and suddenly the same thing happens as in windows. Colored flashing bars on top of the screen and the iMac freezes completely. After this one I can't get it to startup anymore, not even from an external hd or in safe mode. The grey little apple comes on screen and the loading wheel starts and freezes after a minute or so. Safe mode startup the same thing. The status bar doesn't even get half way and the wheel freezes. My Mac: Running latest version of lion, iMac 24", 500gb hd, 3,06 ghz duo core, 4 gb ram, not really sure about the gfx card since I can't check anymore. I know it's nvidia and has 512 mb. External hd is running last version of snow leo. Any suggestions? Regards and Thanks.