I did a clean install of Snow Leopard. Every thing is fine except iMovie is not opening. Whenever I try to open it, it pops up with the following error message - 'Quartz Extreme required' 'iMovie requires a graphics card that is compatible with Quartz Extreme. One or more of your graphics cards does not support Quartz Extreme.' Can some one explain what this means and how i go about resolving this to get iMovie to work?!