Can start in Safe Boot only
iMac Intel 27" Late 2009
My iMac is having serious freezing issues.
When I was watching a YouTube video, my iMac completely froze. I could only move the cursor. I had to shut it down using the power button. It froze a few more times before it started freezing when starting. It would freeze at the Apple logo and the progress bar.
I tried resetting the NVRAM. Started in Safe Boot to close all the programs that hadn't closed properly.
Next I reinstalled macOS Sierra from recovery. That didn't work.
Then I took it to the apple Genius Bar where they did some heath checks and it passed all of them. Next they reinstalled a fresh copy of macOS directly from their servers. It started up fine. I set up an account whilst there and I brought it home.
I tried customizing my Mac and it started freezing again.
Before taking it to Genius Bar, I even swapped the rams to see if they corrupt. But they weren't. I still had the same problem with the other rams.
I don't know what is wrong with this machine. 2.5 years ago I also had the logic board relaxed through Apple.
I can start the Mac in Safe Boot only.