I'm running Fedora Core 16 (with all patches applied as of 11 Feb 2013, AFAICT) on a dual-monitor Lenovo workstation, and can't seem to access my desktop via a graphical login manager. My system boots normally, I get the GDM greeter screen, I select my username and enter my password, and log in. I then get a black screen like Xorg is trying to switch modes before being sent back to the GDM login screen. The same problem happens when I removed GDM and attempted to use LightDM instead.
However, if I boot into runlevel 3, log in via the console, and run 'startx', my GNOME desktop appears normally.
Running tail /var/log/Xorg.0.old
tells me that my previous Xorg session (the one launched from GDM) terminated normally:
[ 1125.791] (II) NVIDIA(GPU-0): --- End of ModePool for Lenovo Group Limited LEN LT2452pwC (DFP-1): ---
[ 1125.791] (II) NVIDIA(GPU-0):
[ 1175.892] (II) evdev: Dell Dell USB Keyboard: Close
[ 1175.892] (II) UnloadModule: "evdev"
[ 1175.892] (II) Unloading evdev
[ 1175.892] (II) evdev: Microsoft Microsoft 3-Button Mouse with IntelliEye(TM): Close
[ 1175.892] (II) UnloadModule: "evdev"
[ 1175.892] (II) Unloading evdev
[ 1175.892] (II) evdev: Power Button: Close
[ 1175.892] (II) UnloadModule: "evdev"
[ 1175.892] (II) Unloading evdev
[ 1175.892] (II) evdev: Power Button: Close
[ 1175.892] (II) UnloadModule: "evdev"
[ 1175.892] (II) Unloading evdev
[ 1175.921] Server terminated successfully (0). Closing log file.
What's going on? What logs can I examine for more information?