I just installed Sabayon, thought I would give a Gentoo based distro a look. Apparently not a smart move. It will not boot and I'm getting a message I've never seen in any Linux distro I've tried:

"Your session only lasted less than 10 seconds."

And it will not boot, either as a user or root.

View details renders this:

/etc/X11/gdm/PreSession/Default: Registering your session with wtmp and utmp
/etc/X11/gdm/PreSession/Default: running: /usr/X11R6/bin/sessreg -a -w /var/log/wtmp -u /var/run/utmp -x "/var/gdm/:0.Xservers" -h " " -l ":0" "root"
/etc/X11/gdm/Xsession: Beginning session set up...
/etc/X11/gdm/Xsession: Setup done, will execute: /usr/bin/ssh-agent -- gnome-session

I found some answers to this problem:
change /tmp permission to 777 (that didn't work, no change whatsoever)
also, someone suggested chown and chmod to the /home/user/.ICEauthority directory. That did not work either.

I've seen where some who have this problem are able to boot as root. I haven't been able to do that. I get same error message both as root and user.

Linux booted just fine.

You're having troubles starting your graphical environment.

Possibly incompatible graphics hardware.

1. You should be able to log in via text mode like this:
2. Once you've booted in, you might find useful error info in any/all of these logs:
3. These are some graphical login files/directories that might have become corrupted, and might be worth removing:'Hope that helps .. PSM