I got caught out by the KB4512941 update last night. Cortana, which I had disabled, turned itself on and immediately started using 75%+ of my CPU: After messing about for a couple of hours in the end I uninstalled the Update to get things back to how they were:   If you get caught the same way then : Go to Windows Update > View update history > Uninstall Updates. In the screen that comes up Double click on the update and then click Yes to uninstall i