Hi All, I have a problem with the internal hard drive inside my iMac (27-inch, Late 2012) model. I have been on holiday for a few weeks and I came back a couple of days ago and booted up my Mac. It worked fine for half a day or so until it kept freezing and crashing. I had to reboot many times and when this happened the mac came up with the "You've had to restart because of a problem" screen. Eventually it got to a stage where the computer wouldn't boot, I messed around extensively in Disk Utility, tried to boot in safe mode which failed, tried fsck to no avail. Ultimately I set up Yosemite on an external hard drive and, through that, I was able to use DiskWarrior to rebuild the Macintosh HD and, using the DiskWarrior preview, get some of my most important files and copy them onto my external hard drive's version of OS X. The problem I am now faced with is to get back onto the internal hard drive's steam. When I used disk warrior to try and replace the directory it failed quoting error message "2166, 2351". I've since attempted to erase and reformat the drive inside using disk utility but I get the error message "unable to write to the last block of the device". SMART status is verified. How would you recommend I proceed? Is there anything I could do to fix the current drive or is it a case of needing to buy and fit a new one? Any help is much appreciated.