I'm using dokuwiki-2006-11-06 (fresh installation) that I installed with the closed wiki option (ACL on).
Everything works fine except user manager (default plugin). I use plain authentication with smd5.
Users could register themselves, but I cannot change anything in the user manager (e.g. groups, or add users there).
In the user manager, I always get (as admin): No users found. 8 users total.
The Search and Add users form appears, but they don't give any results when filled/used.
File conf/users.auth.php is process-readable+writable.
It looks like an already described bug, but
according to http://bugs.splitbrain.org/?do=details&task_id=853
, this bug has been fixed since August 2006.