Well, I searhced a little. And I found out that, when a server doesnt respond, UdpClient freezes. So I stepped over to the Socket class.
I tried some servers I also tried with the UdpClient. 1 server did it, with the 2 other servers, the app freezes.
The same servers now with Socket class: 1 did it, with the other 2 I got an exception the server didnt respond. (time out)
But Xfire can get the information from the servers which didn;t work with my app..
How can I fix this?