it depends if the activation problem is intermittent then it is unlikely to be firewall related problem Firewalls usually require a program to be authorised and I believe it is generally server firewalls that check the traffic content whereas PC firewalls generally tend to block access from a particular program or to a particular port check the software type and version installed on each client PC and compare working/non working installs to see what is different if the IP address/netmask dynamically set or could there be differences there
