Non-root user can't log into X

[erinspice]

After an upgrade from 9.04 to 9.10, my only non-root user on the system can't log in to X. Root can log in just fine. When I type my password into GDM, it attempts to start X but goes right back to GDM without starting X successfully or giving me any error messages. I'm using nvidia graphics drivers and dual monitors, and those work just fine in root's X session. How can I fix it so my non-root user can log in again?

[Rubberman]

Somehow, either the setuid bit on /usr/bin/Xorg got unset or its ownership is no longer root. As root, make sure that Xorg is owned by root and the setuid bit is enabled: chown root /usr/bin/Xorg ; chmod u+s,go+x,go-rw /usr/bin/Xorg
These two commands should set your Xorg executable to the proper permissions. You probably also want to make sure that the /usr/bin/startx script has execution bits set for everyone as well: chmod ugo+x /usr/bin/startx