As I noted, one thing that was GONE gone were my FireFox tabs and bookmarks. Another thing that had disappeared was the new Solitaire thing from W10.
I was trying to download this, and was getting no response from the Microsoft Store thing (the "Get the game" button did nothing), and got into the MS help chat thing with a guy who took over my system and tried installing the store app from the command line (long time since I've seen that!). Once he got that done he needed to reboot my system.
This took a VERY long time, but eventually I was back in.
EVERYTHING WAS BACK. My FF tabs ... my FF bookmarks ... the W10 Solitaire Collection ... EVERYTHING. Well, everything BUT the .txt file he'd put on my desktop with the link to resume the session. No sign of that (so I can't get back to him) ... OR the tab that had the chat window going in Chrome. So weird.
I mean, I searched through all the nooks and crannies of my system looking for stuff (like the .json files for FF sessions), and there was NOTHING there ... but after this reboot ... it's all BACK - and it appears that all the stuff I did today to re-assemble my desktop is GONE (not that this is a problem ... except for having to re-download a mess of video from my camera, the file of which has also disappeared ... but it's confusing as heck).
I really feel like the Universe is going into "let's mess with Brendan" overdrive ...