Problem with connect

I have problem when i setup my server my friends can not get on it. Even if i disable firewall and av. I dont use router. In other games when i setup server is the same problem. Last i updated my OS (Win XP Pro) using microsoft update and i think center of this problem is located there in updates
Someone can help me ?

click here to get hamachi.. just set up a network and have them join it too.. then when you start a local server, people in your network can see the game

i have global ip and 1 month ago i didnt need to have hamachi to play with my friends on my server
And often on hamachi are lags ;/