OS: Windows XP PRO X64 SP2.
Router:Netgear WNR3500L Running Tomato v1.28.7500 MIPSR2Toastman-RT K26 USB Ext
User: Frustrated

Up until yesterday various services running on my machine(VNC, SubSonic, µTorrent) were NAT'd just fine through my router, but now it won't accept ANY attempt at a connection.

I've tried various online port-testers(they all say the ports are closed/stealth) and connecting via my Android phone(Remote Ripple for VNC, Chrome for Java VNC and DSub for SubSonic) on the same network. They all behave as though it's non-existant.

I've also reset the router to it's default settings, no difference.

According to netstat, the ports are listening for connections.

I've done "netsh int ip reset resetlog.txt" "netsh winsock reset catalog" etc. with no discernible difference.

I have also tried connecting a USB-WiFi dongle(thinking my Ethernet had gone bad), didn't help.

I have removed Comodo Firewall(Windows Firewall is not installed), ran MS Security Essentials and disabled VMWare/VirtualBox's various networking doodads(not uninstalled though).

I only seem to have made it worse. Just now it isn't even responding to ping.

Forwarding a random port to µTorrent running in a fresh VM goes off without a hitch.

This is incredibly odd seeing as the ports are forwarded correctly, the services are listening,YOU ARE READING THIS and it freaking worked yesterday.

Maybe you should try with another router to find where the problem is - in your system or in the router.

It obviously was the system considering all other systems on the network work just fine.

I've restored the system from a ghost disk image from a week ago, and all's back to normal.

I would still like to know what would cause a system to not respond despite the ports obviously listening.

I don't know to answer that question, yet it's good that you solved the problem.