Forwarding Ports - Issue

[Lonelywolf]

Ok, I'm now at a crossroads of puzzling and uncertainty:

The problem is how some ports can be forwarded while others can't:

Info I can provide you with:

-I'm on XP (SP3)

-ISP doesn't block ports (confirmed with them)

-Windows Firewall is (TURNED OFF)

-ZoneAlarm Firewall is configured correctly (I even shut it down completely with same results)

-Router has been correctly configured. (Using port 80 to test port forwarding via the router, it was blocked and it was opened by forwarding from the router - so that shouldn't be an issue)

-Modem's Firewall appears (DISABLED)

I'm not sure why, but some ports open up while others don't. Portforward.com is on help whatsoever. I followed all of that in regards to routers but it ain't my problem - I can forward via the router successfully.

Contacting the ISP - THEY DO NOT BLOCK ANY PORTS. I'm 100% sure of this (they kept repeating this to me every time I called them).

Their suggestion was to bring the modem to them and they'll switch it. They seem to be concluding that my modem (Thomson) may be blocking the ports no matter what I do. This one appears smelly and just a waste of time to me, although it could be worth a shot...

So for the actual question:

-Are there programs that can scan specific ports, and conclude WHAT'S blocking them? At least I know the cause...

-Is there any hidden software that cheerfully gives me the middle finger and blocks ports by default that's integrated in XP?

-Does anybody have at least a CLUE of whether I can get these set of ports open or not? I may somehow be able to ignore the utorrent slow speeds but opening ports is something that's truly essential for me in this case, an it would definitely boost utorrent's download speeds.

Thanks for reading and hopefully answering

[Switeck]

Consider Zone Alarm suspect too:

http://forum.utorrent.com/viewtopic.php?pid=271767#p271767