Frozen Throne Dota Hosting

Ok i play Dota (if you havent tried it....do. it is THE BEST custom map every made for an RTS) and I would like to be able to host public games so that my friends and i can team up, and play together.

Anyway I USED to be able to host....but then my windows install got corrupt. It was a copy of XP home, but my cd key was all used up, so i didnt bother re installing that. Instead I went and bought a copy of XP Pro which I am using now. Anyway...I can't host anymore. I have to have port 6112 open to host (TCP and UDP) and it was never a problem in the past.

I know my wireless router is configured right because when I take it to a LAN party, my friends can all host through it if i set their individual IP to be the host, but my computer STILL can't host....even through their internet connection. I thought that maybe my ISP was blocking this port, but last night I went to a LAN and our internet was the same ISP as mine (we are on the same server. We successfully hosted from there using my router(but not through my PC) so I know it isnt the ISP. Anyway...i got a port scanner, and almost everything shows up blocked on my computer.

I don't have a software firewall, and the windows firewall reports that it is off, so that shouldnt be the problem. As i said before I KNOW that the router is configured right...i change it all the time to meet our lanning needs, so that mistake is out of the question. Anyway I was wondering if XP Pro has some security stuff that I don't know about...maybe some stuff that isnt easy to get to. If that isnt it, do you have any other ideas? maybe a program that opens all ports no matter what. because of my router firewall that wouldnt bother me....

If not, any other ideas? It is really frustrating that I have the fastest connection, yet i cant host at all...I don't even know if this is the proper section, but i didnt know whether to put it under hardware, software, or games. anyway....thanks for what help you can give