Since I wasn’t permitted to add to the answer, above, I had to ask the question again. The odd solution to the problem posted above, worked for me:
Turn on a Powerpoint presentation
Press F5 to start slide show
Restart computer (without closing the slideshow)
See if it works [It did work!!!]
And my system is back to normal. I have no idea why it suddenly changed, unless it was another one of those awful Windows updates that introduce more bugs and annoying defaults (like wanting to put everything on OneDrive and launching MS Edge at every opportunity).
