I'm hoping someone here has run into a similar problem.  I lost power to 
my computer and when I restarted it I couldn't get back into the X 
session.  I'm running Xubuntu 9.10.  Basically, I enter the password, a 
few things happen and it asks for the password again.  This continues 
iteratively until I'm too angry and tired to continue.  When I go to 
Alt-F1 console, I see this...

[drm:i810_wait_ring] *ERROR* lockup
[drm:i810_wait_ring] *ERROR* space 65520 wanted 65528

...but then I can login from console and do whatever I want.  What do you 
recommend?  I went to my home directory to look for new files and found 
the file below called .xsession-errors.  That might help so it is 
displayed below.

This guy has a similar situation to me (old dell, xubuntu 9.10) but he had 
an xorg.conf file and I don't have one:

http://ohioloco.ubuntuforums.org/showthread.php?t=1311912

So I can't try his fix.

Mike


----begin ~/.xsession-errors on next line---------------
/etc/gdm/Xsession: Beginning session setup...
Setting IM through im-switch for locale=en_US.
Start IM through /etc/X11/xinit/xinput.d/all_ALL linked to /etc/X11/xinit/xinput.d/default.
/usr/bin/startxfce4: X server already running on display :0

** (gnome-screensaver:1486): WARNING **: Failed to get session presence proxy: Could not get owner of name 'org.gnome.SessionManager': no such name
xfdesktop[1508]: starting up
gnome-screensaver: Fatal IO error 104 (Connection reset by peer) on X server :0.0.
xfce4-session: Fatal IO error 104 (Connection reset by peer) on X server :0.0.
xfsettingsd: Fatal IO error 104 (Connection reset by peer) on X server :0.0.
xfwm4: Fatal IO error 104 (Connection reset by peer) on X server :0.0.
Thunar: Fatal IO error 104 (Connection reset by peer) on X server :0.0.
xfce4-panel: Fatal IO error 104 (Connection reset by peer) on X server :0.0.
xfce4-settings-helper: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.0.
xfce4-menu-plugin: Fatal IO error 104 (Connection reset by peer) on X server :0.0.
xfce4-places-plugin: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.0.
The application 'xfdesktop' lost its connection to the display :0.0;
most likely the X server was shut down or you killed/destroyed
the application.