Anthony Appleyard posted at 3:10AM Fri, 08 January 2016 - #4247905

Does my virus checker (Norton) or firewall stop these updates from working until it gets around to virus-checking them?

Are you sure that Norton is not conflicting with the Windows 10 builtin protection software? I think it's called Defender, and it is an upgraded version of Microsoft Security Essentials. It actively monitors your machine. If you have another protection software, you need to check to see if it will work with Defender. Malwarebytes will.