Hey, I've got one of the late 24inch white iMacs (2.16GHz Intel Core 2 Duo) & I've been having some problems with it lately which I'm pretty sure are the result of a faulty graphics card. The system often crashes when doing large screen refreshes (ie panning in illustrator or switching to a new application. I quite often get errrr bits of the interface left behind. ie when I shrink some thing to the dock bits of the part of the menu bar will still be showing I also get some really really odd lines going across the screen, like rainbow colors almost, normally only about a pixel tall but some times the whole width of the screen. I get the odd pixel lit up too, but it's not a stuck pixel, as soon as I move some thing over it (ie make it refresh the data the pixel goes back to normal.) I'll try and get some screen shots of it messing up if I can. So my questions are: A) Is there any kinda diagnostic tool that I can use to test to see whats faulty. B) What graphics card is in my mac and can I replace it my self? (how hard would that be? Thanks in advance to any one who can help me out. Rick P.S. the Mac is 4 months out of apple care and my nearest apple store is 1.5 hrs away, I don't really wanna drive that far for them to tell me it's going to cost me £1000 to repair or what ever. Oh thats a point, any one know what apple would charge for a replaced graphics card?