The oddest thing just happened, and I've never seen it before --
I was right here on my computer (Win7 Ultimate x64), merrily programming along in Notepad++, when all of a sudden, Windows seemed to "insta-close" -- all of my programs abruptly disappeared, the startbar and everything disappeared as the the monitor went black (soft, not hard). I then heard the Windows logon sound, and it started loading back into Windows, like the computer had just restarted (but the computer definitely didn't fully shut/power down or restart).
There were no running/pending Windows Updates, nor is Windows Update set to do anything automatically (download/install/restart). It happened so instantly that I thought I might have inadvertently hit some kind of "lock screen" shortcut (like WinKey-L).
It was as if Explorer crashed, but there were no warnings or messages, and when it came back, all of my programs that I had had open were gone. Additionally, it seems that some of my usual taskbar icons/programs that run on startup didn't start back up.
The computer definitely didn't turn all the way off. This process probably happened over the course of 2-3 seconds.
The only "intensive" program I had open was Pale Moon, which had about 100 tabs open and was eating a couple gigs of my 12GB memory. There have been no recent changes to the computer, hardware or software-wise.
I've opened Event Viewer to try and find something, but I don't really know where to hone in and look for something like this. I've never seen anything like this before. Any idea what this was?
(perhaps suggestions of places in Event Viewer to review?)