My four year old Apple computer is giving it almost continually. So I am doing something I have never done before.
Well, something I've never done before with Mac OS X. I've done it dozens of times (maybe hundreds?) with Windows and Linux computers.
Reformat, and reinstallation from scratch.
At present, booted up on a thumb drive - it was surprising to me how easy it was. I've had great difficulty getting Linux systems to boot from a thumb drive, and I don't think I've ever managed it with Windows. With Mac OS X, it was easy.
So booted up, and copying the entire hard disk to another USB drive.
Once that's done, reformat/reinstallation. And I will have entered the brave new world.
I blame Obama for this. Or Trump. Or Clinton. Or Putin. Someone.