For the past week or so, my 21.5 Mid-2010 iMac has been almost unusable. It hasn't been fast for a while, due to the age, but this is on another level. One thing to note: since I did a fresh install of Sierra months ago, anytime I boot up the computer, I get a grey screen with progress bar that takes forever to load up. I have tried booting into safe mode, but that doesn't seem to work. After the 30-45 minutes it takes to boot up, any action I try to take on the computer takes several minutes at least to get going. I would like to transfer some things I have on there to an external hard drive, but even that seems impossible at this point. Trying to move my Photos library to an external drive, 45 minutes later the progress bar still says "preparing to move." Here are a few things I've tried doing: Reset PRAM, NVRAM and SMC Check the SMART status of the hard drive, which came back as verified Run disk utility on the hard drive, which reported no issues. Is it still possible the hard drive is failing? I'd like to try other things to fix it, but any action is basically impossible at this point. I ordered the kit and SSD from OWC to see if that helps, but I wish I could know for certain before I install it if that is the issue. Thanks for any help.