do NOT import anything at this point.
im guessing your issue is a old hack that wasnt uninstalled correctly or you failed to remove the xml file for that hack, have you verified that you removed any xml file that you no longer use in the /includes/xml directory?
also in config.php, add this on the 2nd line and save it to the server, then try editing a user.
Code:
<?php
define('DISABLE_HOOKS', true);