Comment 8 for bug 432492

This just happened to me during a routine update - gdm was updated and caused a complete GDM failure "Unable to authenticate" --- I had to go into a terminal screen "C-A-F1" and rollback the update using 'aptitude' - thank goodness that worked!!!

from version 2.28.1-0ubuntu1 to 2.28.1-0ubuntu2

I feel this is a CRITICAL error that would prevent many users from using (and rescuing) their desktop