Cant seem to start a game from WinXP

hi
I am trying to send UDP messages from 1 computer to the other, If I try to send the first message from my WinXP computer it never works but if I send the first message from my Win98 computer it works.
Strangely enough the Winxp becomes capable of sending messages after that first connection is made, I dont know why, does anyone have any ideas?
I disabled the firewall and still the first message was not recieved by the Win98 PC

Do you happen to have an anti-virus program running that also blocks ports? McAfee and Norton both block a bunch of network stuff in the background, unless you explicitely disable it.

thanks for the help,
after more testing I found out it was Zonealarm on the Win98 PC that was blocking the messages.
Thing is though if I start the game from the other PC (windows firewall), Zonealarm lets the messages through.

I dont get why.......

has anyone had experience dealing with firewalls?

A firewall can block both incoming, or outgoing traffic. One of zonealarm's 'specialties' is to prevent programs on your PC from making unsollicited connections to the internet, unless you specifically allow the program in question access.

I guess it allowed the incoming connection because it saw a 'server' program listening on the PC, and assumed it was intentional?

hmm, maybe its because the zonealarm PC has to be the first one to send a message before it can recieve.
(if that is different to what you said)
Thats kind of retarded and annoying, luckily microsofts firewall doesnt act that way and hopefully most people are using that.

With outpost pro firewall (and perhaps too in zonealarm) you can set rules and accept packets received an addressed to a concrete port. In this way you can continue having the firewall protection and also accept incoming packets to a concrete port even when there was not an outgoing packet previously.

thanks, ill check that out