I think we're using an older version (1.42) but looking at the changelog, that shouldn't make much of a difference. We're not running a dedicated server if that makes a difference.
EDIT: Tried a dedicated server. I don't think we set it up right, but there weren't any guidelines we could find for setting up a dedicated server so we winged it. Still didn't work, although in this case we didn't even have a team leader (the host has always been team leader/admin in the past).