mysterious Windows update message

[BobLewiston]

I booted up and got a message from Windows saying that it had done an automatic update that involved a reboot. But there was no mention of this when I last turned off the computer. It's not possible Microsoft turned on my computer to perform an update, is it? If not, then what happened here?

[RedSon]

Sometimes Microsoft performs and update on your computer and then reboots your machine. If the update was run in the background and you shutdown your machine, the next time you started it up it would look like a reboot to the system.

[BobLewiston]

I guess that sounds plausible. Thanks.