If you just want to try my fix skip to end of post. I also stumbled up on this bug in the summer. It took me a while but I managed to solve it in the end for me. (Had the problem on 6 or 7 older computers.) I was sure I documented it here as well but it appears I did not. It was a while ago but I still think I can remember the correct issue.
For me the problem was in the user-session variable in lightdm.conf file located in "/etc/lightdm/". I had set it to 2D to speed things up a long time ago: "user-session=ubuntu-2d" I had a slight feeling that I read something about it and it seams that 2D was indeed dropped in Ubuntu 12.10. http://www.omgubuntu.co.uk/2012/08/unity-2d-removed-from-ubuntu-12-10 This page should probably be updated as well: https://wiki.ubuntu.com/Unity2D My fix: 1) Open file for editing. If you do not know how to do this then there is discussion here on how to edit system files (http://askubuntu.com/questions/92379/how-do-i-get-permissions-to-edit-system-configuration-files) 2) Change row "user-session=ubuntu-2d" to "user-session=ubuntu" 3) Reboot computer Bob or anyone else, please report back if this helps you. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to lightdm in Ubuntu. https://bugs.launchpad.net/bugs/1283826 Title: lightdm hangs after updates Status in GDM: The Gnome Display Manager: New Status in Light Display Manager: New Status in “lightdm” package in Ubuntu: Confirmed Bug description: I've updated today my Trusy Thar installation. I can't login to Unity, with my account, or a guest account. Lightdm hangs after password input, or after I click on the Guest account. Also, I used to auto-login. Now it greets me with the screen where I must input my password. After inputing it, lightdm hangs and I can't login. ProblemType: Bug DistroRelease: Ubuntu 14.04 Package: lightdm 1.9.8-0ubuntu1 ProcVersionSignature: Ubuntu 3.13.0-12.32-generic 3.13.4 Uname: Linux 3.13.0-12-generic x86_64 NonfreeKernelModules: nvidia ApportVersion: 2.13.2-0ubuntu5 Architecture: amd64 Date: Sun Feb 23 23:16:24 2014 InstallationDate: Installed on 2014-01-25 (29 days ago) InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Alpha amd64+mac (20140115) LightdmConfig: [SeatDefaults] autologin-guest=false autologin-user=cristi autologin-user-timeout=0 autologin-session=lightdm-autologin SourcePackage: lightdm UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/gdm/+bug/1283826/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp