Screen suddenly went black while I was working and after ~20 sec a white on black screen appeared saying Windows had shut the PC down to protect... A few sec later a new screen appeared with boot options so I picked "normal". It booted to the desktop. Whew!
When I looked in the Event Viewer there were hundreds (thousands?) of "Microsoft Security client OOBE” Stopped Error 0xC000000D, over the past few days, with the last one right at the time of the crash. PC had been working ok, and MSE updates were being installed daily, and there's a green MSE icon with checkmark on the taskbar.
Anybody notice tons of OOBE errors in Event Viewer recently?