First off, when running the services you are do you have IPtables or IPchains running?

Secondly, at my work I was the main researcher for an AntiVirus Product, we went with a less well known AntiVirus, Sophos. www.sophos.com They full support as400, Unix, Linux, Linux Based SMTP mail, Novell, OS/2, DOS, Windows 9x, Windows NT4.0+, etc.. Their software is very impressive. You can purchase their software, the cd comes with a linux install. It is very easy to setup. I run Sophos AntiVirus on my Linux Firewall (to be firewall, not there yet) and my client pc's on my ethernet network.

-Hope It Helped...
Jason