Argh! ARGH! ARGHHH!
Dammit, now you've got me started on H&D2 multiplayer. Excellent game, hugely more stable than the excellent original, single player is a blast. However, multiplayer is broken for most people with an in anyway usual network configuration. All we get is "Invalid CD Key" errors and it's clear that the support guys on their offical forum don't have a clue why either.
Cheers,
Quboid