Suppress Login Prompt

[Alfred Vahau]

Hi,
I want to suppress login prompt from Gnome after a browser is closed.
Ubuntu (Warty) has been customized to skip the login prompt the first 
time it boots.
When closing down firefox, Gnome presents the login prompt when I don't 
want.

How can the login prompt be suppressed?

My .xsession file in /home/username/.xsession has only one entry i.e 
/usr/bin/firefox
to fire up the browser automatically.

Thanks,

Alfred Vahau