'User Accounts' can break the system administrator account

How to reproduce the bug:
1) Install Ubuntu 11.10 or 12.04 (development branch), and as normal, create a administrator user during the installation.
2) Open Gnome Control Center (also called System Settings), and open User Accounts module.
3) Pick the only existent user (the Administrator user created in the installation), click on Unlock and enter the user password to can do administrative tasks.
4) Click on 'password' to configure password stuff for the current selected user.
5) On 'Action' list box, select 'Log in without a password' and click 'Change' to save the new configuration.
6) Log out (close user session) and Log in again, now you don't need to type the user password to log in.
7) Now try to run some administrative task using sudo or pocicykit to authenticate, they will ask you for your password but they won't accept your old password and neither accept a blank (null) password. This happens also for 'User Accounts' module.

The result is: you cannot do administrative tasks now in Ubuntu.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: gnome-control-center 1:3.2.2-2ubuntu2
ProcVersionSignature: Ubuntu 3.2.0-10.17-generic-pae 3.2.1
Uname: Linux 3.2.0-10-generic-pae i686
ApportVersion: 1.91-0ubuntu1
Architecture: i386
Date: Tue Jan 24 02:27:36 2012
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Alpha i386 (20120121)
SourcePackage: gnome-control-center
UpgradeStatus: No upgrade log present (probably fresh install)
usr_lib_gnome-control-center:
 deja-dup 21.2-0ubuntu4
 gnome-bluetooth 3.2.1-1ubuntu3
 indicator-datetime 0.3.1-0ubuntu4