Help! I think my iMac has died!!! Just not booting at all. 1. iMac chimes when I press the button. 2. Apple logo appears along with spinning icon + bar appears at bottom of screen which gets about 1/10th of the way along and then the whole thing just turns off again. Can't even get it to run in safe mode. Thought I would re-install Snow Leopard, so put the disc in and held down 'C' and brings up the install panel, however the hard disc is not available to select for a destination to install. Next I run disk utility from here. I run Verify Disk on the HD and it says 'Invalid Node Structure' 'Could Not Be Verified'. 'This disc needs to be repaired. Click Repair Disc'. I do this and after a minute during the 'updating boot support partitions for the volume as required.' process it says 'Can't repair disc. Back Up Files, reformat disk and restore backed up files'. So - how do I back up from this position, (my last time machine backup is April 13th - I know I know, I'm an idiot!) as by telling me to back up files it would seem to indicate that it is possible. Anyone offer any assistance? It's a 20'' iMac, 2.4ghz, core 2 duo, 2G Ram, 500GB hard disc (about 45GB free). About 2 years old.