hosting/server problems

Hi
First of all sorry for my english and my weird sentence building
I will get straight to the point
I have a problem with connecting (or sometimes even seeing) servers created by my friends (who are running windows xp) and vice versa.

We have a simple-hamachi-lan and i usually was hosting servers for ventrilo some games etc.

When I start a ventrilo server, even I can't connect to it
I tryed with my IP then my hamachi address and nothing


I have my tcp and udp ports unlocked on my router , I've set it up in the server but it does not change anything

I know there is not much info in this post ,im a little tired from all the hours trying to solve this ... I will update soon.... please help if you can

My first step would be to remove the router to be sure it is the OS. No sense wasting time trying to fix one or the other without knowing for certain the cause.

You may want to disable windows firewall to and uninstall any AV software to help narrow it down.

ok so

I allways disable the windows firewall on first boot :)
the router is fine (on previous OS everything was ok)
I also turned off my personal firewall and av ...

I have a hunch that there is some kind of data in/out blocking service that does not allow small aplications to send packets to the network.