I finally bit the Keychain Access bullet and upgraded to 10.13.4...and Finder was corrupt: command-I, command-C, and other windows and screen artifacts wouldn't close by ANY means other than quitting Finder, and neither "Restart" nor "Shut Down" worked, and "Sleep" flashed on and immediately off, both from menu bar and control-power pop-up. (Maybe more, but I threw in the towel at that point.)

Back to 10.12.6....waiting for 10.13.5.

Aaargh!!!

The new Great Equalizer is the SEND button.

In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire