Hmm... I'm having the same error too.
The odd thing, though, is that it only happens if I've been on another server during that session.
For example:
If I launch BL and start a server straight away, it works fine.
BUT... if I launch BL, join a different server, and then try to start a server, THEN I crash.
This also occurs if I try to launch a server for the second time during a session.