btw this is a manifestation of one of the most incredibly mind-bogglingly awful things about W10: microsoft has made it Extremely Difficult to ensure your system stays up for any amount of time

on any day you might return to your PC to find it at the log-on screen, your system having gone down at some point in the last however-long you were away to apply almost-unavoidable patches

i've heard of it happening when people are on their system doing work, and losing work. it's so fucked.