net send_packet help

so guyz i have tried to make a dedicated server on my pc using cs 1.6 (tried with steam too)and when the game starts and i give my friends the ip address it disconnects me from the internet and i get this msg ""net send_packet:no error"" after i press ok the internet  reconnects automatically and then i have to restart the pc to create new dedicated.So i posted this in order to get some help...so thnx

THE ONLY STRANGE is that i sometimes can play normally but this happens when i start the game or when i am already in the game and when this happers the server kicks the other players and says"problem connection" please someone help i have tried to find out everywhere an i got it but there was no possible answer...thnx in advance:D