After reading through the subforum list multiple times to make sure I wasn't being stupid, I'm pretty sure the Chaos Daemons forum has disappeared.

Yeah, a fair amount of the sub-forums are having problems. Please see this post:

http://www.librarium-online.com/forums/site-feedback-support/121207-missing-threads.html


And this announcement:
http://www.librarium-online.com/forums/site-feedback-support/announcements.html

Please check site feedback and support to see if there is another thread on the same problem :)