It seems that the update did not make a correct registry entry. If you haven't solved it, or if it happens again....
You could try this which may force a refresh of shell icons
Click on the start button, bottom left In the search box type in Default Programs In the box that comes up click on the link Set your Default Programs Click on any of the links on the left hand side Click on Set this Program as default button Click on OK Switch your pc off and then reboot.
The Norton installed is a trial version of an anti virus which protects you when you are using the internet - you can choose not to have this if you want to use a a different one.
Norton Internet Security is a complete packge (antivirus, firewall, spyware protection, adware protection, etc.) Windows Defender is only Spyware protection program, it does not get rid of viruses, it get rid of spyware/adware, trojans. You can have 2 spyware programs on your computer but its not good having 2 antivirus protection program, they will clash with each other making either to not work properly. Window Defender and Norton work together.