Mid 2007 iMac here - 20'' / 2.4 / 4GB RAM / 500G HD About a month ago after ripping a DVD with Handbrake it locked up, I did a hard restart but it failed to boot. Took it to Genius Bar and they got it going again by reinstalling OSX. Told me to reinstall from my TM backup once I got it home. Unfortunately I couldn't get it to do this as it couldn't find my back up drive. During this process it locked up to the grey screen telling me I had to restart by holding the power button in - then got stuck in a continuing cycle of this. Back to Genius Bar yesterday and once again they reinstalled OSX while I waited. All fine - got home, restored from back up and finally got my old desktop back. Stuck in another DVD to rip with Handbrake last night and once again after it finished - it locked up. Had to do a hard restart again - and once again, I'm now stuck with getting to the grey apple screen and spinning ball. They ran a brief hardware check while I was at the apple store and everything checked out OK - but does it sound like it's on it's last legs? 3 years old isn't that old, but I guess it's struggling. I don't really know what else to try apart from a continuing cycle of weekend trips to the Apple Store for re-installations.