I have been trying to get beta11 running with "frozen_nick" on. Adding $params["frozen_nick"] = true; to the default index.php, it goes into an endless loop of:
27/07/2007 12:44:02 * guest569 changes his/her nickname to guest194
27/07/2007 12:44:07 * guest194 changes his/her nickname to guest423
27/07/2007 12:44:12 * guest423 changes his/her nickname to guest221
27/07/2007 12:44:17 * guest221 changes his/her nickname to guest505
27/07/2007 12:44:22 * guest505 changes his/her nickname to guest294