I have my computer’s (one XP one Vista) set up to run as Media servers. As soon as I installed CIS, my PS3 could no longer see my computers. Your assistance is appreciated. I do not know if it is the firewall or the Defense+
Can you show us a screenshot of the Firewall logs of around the time the PS3 is trying to connect? The logs can be found under Firewall → Common Tasks → View Firewall Events.