Left my machine running during tea, because I had a metric fucktonne* of work open - apps and various file explorer windows - and wanted to come back to it.
Came back, the machine was off. Nothing - repeat, nothing - in the event logs. No power cut either, everything else in the house running fine. Windows update (always a bastard) had not run.
Disturbed, I had a root around to find that the last file before it died was telemetry - specifically, Microsoft Office Click-to-run. Programs and Features is now showing Office with an install date of today.
A bit of Googling reveals the following:
https://social.technet.microsoft.com/Forums/en-US/cd971c47-bb24-49bc-9b53-6ec1cbdc9870/windows-update-no-office-2016-updates?forum=win10itprosecurity
i.e. if you have any Click-to-run version of Office installed, then updates are controlled within the applications, independent of Windows Update on the machine.
I have no idea whether the update-and-shutdown-and-screw-your-workflow was by design, or if something failed, but updates are now disabled on this computer. I'll decide when to run them, thanks very much.
