Every now and then (much more recent lately!) I come across a problem where, should my girlfriend and I be playing a multiplayer game, the games start up, the world map shows, and... the game draws immediately, saying one of the draw messages (eg, dull game, etc). It then says "Your turn, [next worm]" as the game fades away. We've tried doing a lot of things to fix this but I simply can't figure it out. Any ideas?

verify the victory conditions don't result in a draw upon start.

Sounds to me like you have your game set up to end once sudden death starts, and for sudden death to start immediately.