Hey everyone, I've been having problems with my 2009 27" iMac. It just started acting up, like, getting stuck on the grey screen during boot, not being able to wake up after sleep, etc. Here's what I've tried (in no particular order): Resetting the PRAM Resetting the SMC Reseating the RAM Removing 3rd party RAM (leaving only the stock chips) Removing Apple RAM (leaving only 3rd party chips) Replaced the HDD Reformatted the new HDD (multiple times) Treid reformatting in a difference scheme (it then forced me to use GUID to install OS X) Reinstalled El Capitan and Yosemite Tried doing two partitions with a different copy of OS X on each Ran First Aid from inside El Capitan Ran First Aid from the recovery partition Booted in Safe Mode and ran First Aid where I get the following message: "Problems were found with the partition map which might prevent booting" I've tried running the hardware check thing by holding "D" during boot but it just got stuck again. After waiting on the grey screen for 20 minutes, I held down the power button to force it to shut off. So far, nothing has seems to make any difference. The only way I can get it to boot reliably is when in Safe Mode. I've searched all over and can't find any solution. Does any one have any ideas to help a fellow out?