Ubuntu 10.04

Hi guys. I'm not sure why but quite recently, my ubuntu desktop started bringing up the command prompt login screen after booting. I want GDM to start up by default.

I can manually bring up GDM by typing:

sudo service gdm start

or

sudo /usr/sbin/gdm

but I want something more permanent.

The contents of /etc/X11/default-display-manager point to /usr/sbin/gdm

The chkconfig status for GDM shows that it's off on all run levels... could that be it? I tried running:

sudo chkconfig --add gdm 

and just got errors...

Any ideas? How can I get GDM to automatically come up again? Any/all help is appreciated!

-M