Hi all, I think that I have successfully diagnosed that my iMac's HDD has failed after three and a half years of use. It is a stock Apple installed 1TB SATA drive. I used to keep my computer on 24/7, unless knowing that I would not be using it for more than three or four days, in which case I would shut it down. I am wondering whether this strategy killed the HDD. I am now operating a policy by which if I know that I will not be using the computer for more than half an hour, I will shut it down. What do you think?