Normally Norton support can fix your situation.
You can contact Norton support for NSS at Norton.com/comcast, start a chat support session, report the issue. Please use the CHAT option on the right hand side of the following link. Be sure to ask them to check their data base and see if you are shown as Comcast customer - if you are not in the data base as a customer, all the uninstalls/reinstalls in the world will not permit Norton to comtinue running.
Let us know if this helps.
You can have a look at the following if you desire to try to unnistall/reinstall on your own:
Please let us know how things go.