Imported From: http://groups.google.com/group/in-portal-bugs/browse_thread/thread/73a6d5ebda3a4b2c#
Tested on my local 520: Go to Configuration > Advanced, and hit Save:
Exception: Query method is called in class ConfigurationItem for prefix conf in /www/520/core/kernel/db/dbitem.php on line 1476
Do you have same behavior on your machine, guys?