I'm on a Windows Server 2003 machine, and after some light to moderate network use, the server occasionally drops all IP traffic. It takes a while to get into this state, and there's nothing obvious that triggers it. It's possible to get the server out of this state by terminating (cleanly or abruptly) or restarting any applications that [believe that they] still have TCP connections open. The server in question becomes unreachable to the rest of the network and it is unable to reach the rest of the network, so the upstream gateway is not involved.
What IP traffic have I observed dropping? TCP, UDP, ICMP.
What kinds of applications are running? Typical workstation (Terminal Server) workloads.
Is there a firewall running? Yes, Windows Firewall. Disabling Windows Firewall after the problem occurs has no effect.
Is there an AV program running? Yes, McAfee VirusScan Enterprise. Disabling VirusScan after the problem occurs has no effect.
So, wizards, how does one trace the path for IP datagrams heading through the layers of the network stack to the bitbucket?