you can just stop Symantec antivirus and Symantec antivirus definition watcher service that is enough.
Then replace the root certificate and paste the grc.dat in c:\doc & set..\all user\app..data\.......\7.5
then start both the services that is enough.
Check if the firewall is disabled or port 2967 is open.
the quarantine agent and central service will be there on compute having Quarantine server and Console installed so it can be ignored.