What a pain this is. Two weeks ago my dual 2.0 g5 started displaying "fan failure" in the system.log so I took it in to the apple store. The genius couldn't determine anything so he checked it in for me w/ a $75 fee. It was 2 weeks out of apple care. Just my luck. I figured it was the powersupply but for $75 I'd let them diagnose and it let me know for sure. Almost two weeks go by and no call. I finally get impatient and call them up. The guy says, "oh we changed your video card which fixed the cold boot problem." It'll be $250 I told him that it had been doing that since I purchased the machine 3 years ago, multiple calls to apple tech support and bringing it into the apple store never saw a fix, that it is pretty silly to pay this money NOW, and for a problem I didn't even bring it in for. He told me that it also fixed my other problems so I said OK fine, and went and picked it up. I get it home, plug it in, boot up and the fan failure message is still being displayed. Oh, and it still doesn't cold boot. So essentially I paid $250 and they fixed nothing. I swaped hard drives (I put a fresh one in there, installed OSX to verify the message didn't have anything to do with my OS) and started her up. Everything loads fine but the screen will go black every few seconds. It only lasts a second or two but it is obviously pretty unusable. I swap the hard drives back to the fresh one, and it's fine. Swap back, make sure everything is hooked up properly, flashing black. Screen off, screen on, screen off. Seems to happen mostly when in finder. e.g. when I have firefox and a web page open it is fine, but if I scroll around, click, etc it goes wacky. The last thing I noticed is that 512mb of my ram is gone! I had 2.5gb and now the system only has 2.0gb. I opened it up and sure enough, my two 256mb apple sticks are missing. What the heck do I do? I called the apple store and they wouldn't help me over the phone. They said I have to bring the computer BACK in (it's 30 mins away and there are no open appointments all weekend and it's virtually impossible for me to make it there during the week due to my work schedule), and drop it off with them to look at it. As it is now, I paid $250 for a repair but my computer is now in worse shape than I gave it to them in--and is missing hardware! Does anybody have any clue why the screen would be flashing like that with my previous installation? If I could get that to stop it would at least be usable until I could get the other problems resolved, but it's going berserk right now! Sorry for the long post but hopefully somebody can come to my rescue.