Multiplayer issues caused by differing OS?

[Carwyn]

I've been playing MP Civ IV for a long time. Recently I upgraded my computer and installed Win XP Pro 64 bit (instead of the 32 bit we've all been using). Now when I play MP with my friends, I get OOS in the early game. Is there something that I need to do with my OS to fix that, or should I be looking somewhere else?

Thanks!

Edit: Would my installing from the Game of the Year Edition cause OOS if my friends are using another version of the game? I had been using another version of the game to play in the past.