KDE Login Manager leaves unexpectedly

[Pieter Donche]

In FreeSBD 7.0, set up KDE 3.5.
I want to change settings in KDE Settings/SystemAdministration 
/ LoginManager  (no shutdown possibility for a non-root privilege user)

This asks for the root password, I enter the correct root password,
click OK, and that dialog window closes and I back in the desktop ...

Why ???

(the root password is certainly correct, if I change a letter, I get 
Incorrect Password; try again)

I can choose 'ignore' and continue with non-root privileges, but when
I want to change something that requires root privileges, same dialog
box and when entering correct password, the dialog window closes...