After much head scratching I found that somehow the Windows Firewall had switched itself on, so Norton had switched off Smart Firewall and would not switch on. ( Two Firewalls On always cause problems.)
I could toggle it to ON, but running Fix turned it off again.
After manualy switching off the Windows Firewall, and switching on the Norton Smart Firewall again and rebooting, the problem seemed to go away.
Same issue here as GORPY1 on my XP pc and version 21.1.0.18.
To be honest, I do not pay attention at all as I know that NIS works and my system too !
If this issue is 2+ years old I doubt that it will be fixed, but at least the engineers should provide a dialogue box including what was fixed so the user is aware of the potential problem and the solution applied if a problem was found.