Can't access Gnome login preference

[David Shultz]

Hi! I'm trying to access Gnome Login Window Preference from Gdm before
logging
to Gnome. But when i give password and hit enter to enter preference, I get
blank screen and the system goes back to GDM login window. Can anyone help
me detect why i can't access Gnome Login Window Preference from GDM? I've
debian etch on my computer. Thanks.