Quite easy, his wife hit upgrade and entered the password and it installed the upgrade and the computer slowed down without his help. Normally if you install some kind of update you are responsible for everything that goes wrong from then on, including the computer slowing down.
As an example I installed Windows 8 -> 8.1 for someone as IE10 wouldn't work with some website and IE11 needs Windows 8.1. Everything that's wrong with it is now Windows 8.1's fault, including IE11 which doesn't work with some other website.
Eventually I installed Firefox which seems to have kept him quiet for a while.
Biting the hand that feeds IT
