Verisign Certification Expired?

I have been having problems with my pop email account and, this morning, found a message informing me that my Verisign Certification needs renewing. I am able to continue for the time being but I am having trouble finding out how to do this

Background: I have just installed Norton on this machine. We have had an account with Norton for some time and this is the second machine it is installed on. The machine is new (Dell XPS 8700) which came with McAfee which I uninstalled prior to installing Norton.

Any help would be greatly appreciated.