Can't log in gnome session after changing display

[Tom H]

>>> Problem: cant' log in the gnome session after changing display
>>> resolution to 1280x768, although I still can log in the gnome
>>> session by typing 'startx' after booting up Ubnutu as the
>>> recovery mode (text command mode?).

>> In console mode
>> sudo /etc/init.d/gdm  //or kdm
>> sudo dpkg-reconfigure xserver-xorg
>> sudo /etc/init.d/gdm start  //or kdm

> It didn't fix my problem.
> After running the first commands, I got the following error message.
> "The script you are attempting to make has been converted to an Upstart job,
> but //or is not supported for Upstart jobs."

You have to use upstart commands:
sudo start gdm
or
sudo initctl start gdm
or
sudo service gdm start