NVIDIA Firewall Problems with AVG AntiVirus

I just got a new PC with a ASUS A8N-SLI Premium MoBo which came with NVIDIA firewall. I have been using Grisoft's AVG antivirus software and eMail scanner. These 2 packages do not play well together. I cannot get my mail in Outlook Express 6 if both are running. If I close down AVG, I can send and receive mail in OE6. If I close down NVIDIA FW and activate AVG, I can also get and send eMail. If they are both working, no send or receive eMail. Does anyone have a clue on how to get these 2 softwares to work together? Keep in mind I am a complete novice on firewalls and all the terms that they entail.