Thanks for the suggestion.
Well, tried clearing cache and cookies again just to be sure, then closed down Chrome and Edge.
Restarted, now I can no longer login under the Edge guest profile either!
Rebooted entire laptop, no go.
I know this same thing happened a little while ago, don't know how I got it working again. Or maybe there was another Window's update that had corrected it for me, not sure.
But it sure seems like it has something to do with the last Windows 10 update.
1978 Gibson Les Paul Standard, Cherry Sunburst