Can't map network drive on a VPN

With Comodo v I can connect to the VPN but I’m unable to map to the network drive (I get a “The network path **** can not be found” error.

If I disable the firewall I can map the drive. Then if I Disconnect from that mapped drive and reenable the firewall I AM able to map the network drive with the firewall turned on. If after restarting Windows I merely turn the firewall off and back on again I can not map the network drive.

Somehow something is getting flipped to “on” when I do the above chicken dance. How can I get the Firewall to allow me to map the network without having to turn it off and back on again?

This is on a WinXP Pro SP2 system.