After updating Ubuntu, I restarted the computer. The Light DM Display screen came up. I thought nothing of it until I tried logging in. Instead of logging in, it would go black for a second and bring me to the login page again. I've tried all sorts of commands from online Ubuntu support groups. Nothing has worked. My laptop is 5 yrs old, so I don't know if it's telling me it's dead.
ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: lightdm 1.14.2-0ubuntu1.1
ProcVersionSignature: Ubuntu 3.16.0-34.47-generic 3.16.7-ckt8
Uname: Linux 3.16.0-34-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.7
Architecture: amd64
Date: Thu Nov 5 20:38:03 2015
InstallationDate: Installed on 2014-03-18 (598 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
ProcEnviron:
TERM=linux
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=en_US.UTF-8
SHELL=/bin/bash
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)
The log shows you are logging into your session, but it quits after 10 second. Can you try this and then look at the contents of ~/.xsession-errors after this occurs?