gdbm automatic login doesn't work in the xfce spin

[Sam Varshavchik]

I installed the F16 XFCE spin on this laptop. I copied /etc/gdm/custom.conf  
from another Gnome machine that has automatic GDM login working just fine.

On this machine though, the "Automatic Login" gdm banner comes up for a few  
seconds, then inexplicably disappears and gets replaced with a regular login  
banner.

What's up with that?