I have this issue as well and it only occurs when you log out of KoL (but do not quit Mafia) and log back in. It will actually show the chat log of the previous session and after that no longer refresh any chat windows. I'll do a quick test to see at which revision it started to occur.
EDIT...
I've been having this exact same issue ... Mafia hangs when logging back in after logout. I actually have to kill Mafia through Task Manager (Windows comes back with "this program is not responding") I've actually gone back to older builds and experimented a bit and this problem popped up in...
Upgrading to just a newer mafia version wasn't enough in my case.
I also had to remove all the snapshot_*.txt files under data/ prior to running the script to get this to work again.
Working OK now with r8985 (most recent version at the time of posting)