Hey,
I have a teeny tiny problem.. well I can't join games hosted on the port 80 (I really need to), it fails at Checking Status of host :(
But when we set the port to 17011 (I believe it's the default port), everything works fine. I can also join games hosted at worms2d.
The port 80 is used almost everywhere and that's why I think it's something related to worms.
Any help ?

It could be that somewhere between you and the host lies a transparent HTTP proxy, which mungles HTTP requests.

Can you record a packet log (http://worms2d.info/Recording_a_packet_log) and post it here?

This hasn't been mentioned: Ensure both of you (including the one joining the game) have the latest beta update.

This hasn't been mentioned: Ensure both of you (including the one joining the game) have the latest beta update.
We all have the latest build.

Can you record a packet log (http://worms2d.info/Recording_a_packet_log) and post it here?
Here it is : http://www.mediafire.com/?aq5kdtva9ndig20

On which machine did you record this log? On your computer, and you tried joining a game on another computer hosted on port 80?

If so, then the cause seems to be an antivirus/firewall program on your computer. It's not letting any bytes through, because it's probably expecting to see a full, valid HTTP request.