Here's a thought
>BT confirmed: "There was an unusual power spike on Saturday evening which disrupted services from the BT Tower for a short time. We are looking into the circumstances behind the outage."
Maybe when the X-Factor started everybody went to put on the kettle whilst waiting for the adverts to start creating the power surge which caused the outage.
Note: This is just an educated guess as I've never seen the programme and couldn't even if I wanted to, for all I know it might be quite a good show.