SoCal Sam
Lunatic Member
One reason this could happen is that a file or files on your hard drive somehow got corrupted, which does happen sometimes. How old is the hard drive in your computer? It may be worth replacing if it's getting up there in years. A fresh install would fix this problem just like you experienced. A lot of computer issues are hardware problems but software gets the blame most of the time.
Now that you've re-installed, have you updated the machine again? If so, are you seeing the same bad behavior? If not, it was probably a hardware problem.
Hard drive is a near new SSD. Computer is Mid 2011 which I bought broken and repaired the AMD GPU which is a known weakness. It ran High Sierra for a couple of years. Because I do not know full history, I can't discount hardware problems.
I just installed all updates and it seems to be behaving as expected which is shutting down on command. Thinking back on my first install, I messed with the screen saver and power settings through the GUI. I also installed and uninstalled a fan control program.
