My first time here so be gentle, please. I've got a 2010 iMac and it developed a grey death screen a week or so ago. Disk utility (from the install disk) can't repair and suggests backing up. Bought an external hard drive to do this (of course hadn't done so before) but it won't back up fully. Don't want to reinstall the OS as I haven't got a full back up. Before taking out the hard drive and sending it off for expensive data recovery I thought I'd try Diskwarrior as good things are reported about it. Diskwarrior 4.4 arrives today from Amazon but it won't boot: after a few seconds of grey screen the DVD ejects. Quick research shows that there appear to be some compatibility issues with Diskwarrior and some later iMacs (not made clear on Amazon of course). My install disc is Snow Leopard, v 10.6.3, though I think the iMac OS is probably later than this. My questions are these: 1. Are the reports about incompatibility with Diskwarrior correct? 2. If so, is there any way to force a Diskwarrior boot from the internal DVD drive? 3. If not, there seems to be suggestions out there that I can save my install disc to my external drive (a WD My Book), boot from the external drive and then (presumably from the internal drive) run Diskwarrior. Is this the case? 4. If so, how do I save the install disk to the external drive? (I have a Macbook to hand) and having done that, how to force a boot from the external? (I am using a non-Mac usb keyboard as the wireless mac keyboard is not connecting). Alternatively, could I copy the Diskwarrior dvd to the external drive (using the Macbook), boot from the install in the iMac internal drive and then run Diskwarrior from the external? Again, if so, what are the steps for doing this? Apologies for the length of this post but I am a real beginner at this stuff. Thank you.