I commented out a bunch of stuff and disabled AIGLX in the Serverflags section, but it's still behaving the same way. It works perfectly if I break my xorg.conf, causing it to kick me to the command line without an X session, then fix it back up and run startx... but if I reboot and login as usual, I get "unable to open display: 0"
grahambae@solideogloria:~$ cat /var/log/Xorg.0.log | grep WW
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(WW) The directory "/usr/share/X11/fonts/misc" does not exist.
(WW) The directory "/usr/share/X11/fonts/cyrillic" does not exist.
(WW) The directory "/usr/share/X11/fonts/100dpi/" does not exist.
(WW) The directory "/usr/share/X11/fonts/75dpi/" does not exist.
(WW) The directory "/usr/share/X11/fonts/Type1" does not exist.
(WW) The directory "/usr/share/X11/fonts/100dpi" does not exist.
(WW) The directory "/usr/share/X11/fonts/75dpi" does not exist.
(WW) fglrx(0): board is an unknown third party board, chipset is supported
grahambae@solideogloria:~$ cat /var/log/Xorg.0.log | grep EE
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(II) Loading extension MIT-SCREEN-SAVER