Things that only happen on Windows:

1. Windows updates itself with a security-update
2. On next reboot, upgrade procedure fails and reverts changes
3. Repeat

You cannot prevent the update, you cannot shutdown or reboot without the update and it takes around 30 minutes to install and revert every time during boot.

There is a saying; "Insanity is doing the same thing over and over again but expecting different results." I therefore officially proclaim insanity of my Windows installation.