Network error 38.0 when trying to join a multiplayer game.

[Rawket]

So, I installed Brawl Busters not too long ago. Struggled to actually launch the game at first, but after trying again today, it finally decided to be nice.
Made my character (the ability to choose from a range of body types is a nice touch), did all the single player quests and decided I'd give multiplayer a go. Joined a room, clicked Ready, host started the game, it loaded... then suddenly, I'm back on the main menu with a window saying something about a 'network error 38.0'.

I have tried joining several different games so I don't think it's a one-off. Has anyone else experienced this, and how can I get around it?
I have a very good connection and I'm a bit disheartened because the game has been enjoyable for me so far.