I've searched high and low for a solution, tried everything I know, but still cannot get my two PCs on a LAN to play a network game through TCP/IP. Here's what I've tried so far: (1) turned off Norton firewalls (Window firewalls are already off), (2) verified DirectX versions are up to date, (3) updated to latest patches, (4) tried hosting from each PC.
The problem is that when one PC tries to join a game on the hosting PC, it cannot join because the game states the host has the door shut. But it's wide open! One PC is XP Home Edition SP3, the other is Vista. I can see the available games to join, and the host PC sees the other PC trying to join, but it's a no go each time.
Am I trying the impossible?

Because I'm surprised about this error, I ask the dull question if you updated both game clients?^^

Both game clients have the latest patches installed (frontend icon is showing 105)

Is Norton thoroughly killed? In my experience it likes being a giant spanner in the works for anything network-related.

I believe Norton Internet Security is disabled on both machines - smart firewall turned off, antivirus autoprotect off, silent mode on. One thing I noticed is that the XP machine gives an option on the first menu upon loading to have what I call the movie action bar open or closed. The Vista game client never has this movie action bar visible. I've tried it both ways on the XP machine with the XP hosting and then the Vista hosting a game.
The host machine shows up as a green circle - I can see the number of teams joined. But when the 2nd PC tries to join, it's given the door shut message.
I'm wondering if perhaps my router is causing a problem. The XP machine is wired to the router, and the Vista machines is wireless through this router. It's a 2Wire gateway router. I'm just grasping at this point, out of ideas to try. I haven't played the game in years, but thought it'd be fun to introduce the kids to it so we could play each other. We can do it with one machine, but multiple PCs is so much better. *sigh*

The only suggestion I can make is to ask if you have applied the correct patch.
There are a North-American, a European and a Polish patch.

Also, you may check out this dedicated Worms 2 forum:
http://adamrgolf.selfip.com/worms/forum/
I believe there are some 3rd party patches and other stuff that might help you.
Plus people who exclusively play W2, thus, have quite some knowledge.
One thing I noticed is that the XP machine gives an option on the first menu upon loading to have what I call the movie action bar open or closed.
It's a clapper board.
And I've seen that before:
http://forum.team17.co.uk/showthread.php?p=668196#post668196
Sadly, the two posts I linked to in that thread a bit down, don't work anymore.
Apparently, restarting the computer fixed the missing clapper board for that guy.
We can do it with one machine, but multiple PCs is so much better.
In my opinion, there is no better experience in any Worms game than a good old hotseat multiplayer games.
I had the most excellent session with several friends back in 1997 with Worms 2, which haven't been topped yet by years of playing WA online later.

The only reason for a networked game would be the invisibility utility in WA, which is disabled in hotseat games as it's obviously useless there.

I remember Liksis or someone made an article on this, it might have been iP Regulator. They said something about a change between Direct x 9.0b and 9.0c causes the network functionality to fail.

Try playing via IPX, if IPX isn't available then simply install it D: should be provided with every Windows since Windows 98 (can't remember if 95 had it).