Web Server 2K3 stops accepting Internet connections

Browser from Internet side of firewall just says Connecting to 216.31.161.4.
This only happens sometimes then I have to disable and re-enable the NIC.
Can find no logged messages associated with this: event logs, IIS logs,
HTTPerror. Firewall forwards http to port 80, no other traffic allowed, only
Web Server and one pc inside firewall.

This info is very sketchy because I'm not sure I'm looking in the right
place for answers but don't really know where to turn. I can't see any
indication that it is an IIS 6 problem but I just don't know. IIS and
website is accessible from inside LAN through second NIC. Also, accessible
from the one pc inside the Internet firewall. Firewall seems to have no
errors. Restarting it or even swapping it out does not clear the server.
Only disabling and re-enabling the network connection (or rebooting the
server) gets things going again.

Any help or direction anyone can give me would be very much appreciated.

Thanks,

Buck