well...
This is tricky, and if it is a software problem related to the nvidia firewall then its even more tricky. You see, the nvidia firewall is actually not software based, it is embeded into the nforce chipset, so it is a hardware firewall.
One way to get rid of the firewall I have seen is trash the chipsets, and uninstall the nforce software completely, reboot the machine, and then reinstall them off the motherboard's cd. During the installation wizard make sure that the 'network access manager' is not installed.
or go to
Start > Programs > NVIDIA Corp > Network Access Manager > Web-based Interface > Basic Configuration > Off
See what that does