LOL! Good one. 2020 indeed.
I did not have gadgets turned on, did not have Aero Peek turned on, did not to the best of my knowledge have any of the items listed -- except for IE 9. Might have the touchpad Intellipoint thing loaded, don't know. Sure enough, out of the blue, Alt-Tab
FAIL. That's how I came to be here.
Sure sounds like the common thread over the past 2 1/2 years is that by changing some setting - different for each instance of the problem - which causes something in the graphical interface to reload, the problem goes away until . . . well, until it comes
back.
For me, switching to Classic interface solved the problem.
Which is fine, because that's what I'd wanted all along, just couldn't find it at first.