Stephan, try removing .Xauthority file from your home directory and see if it helps.
-- You received this bug notification because you are a member of Desktop Packages, which is subscribed to lightdm in Ubuntu. https://bugs.launchpad.net/bugs/829247 Title: cannot login as a user Status in “lightdm” package in Ubuntu: Invalid Bug description: I cannot login as a user. After entering the passwort lightdm appears again. But I can login as a guest. Problem stays even after new install of Ubuntu. ProblemType: Bug DistroRelease: Ubuntu 11.10 Package: lightdm 0.9.3-0ubuntu3 ProcVersionSignature: Ubuntu 3.0.0-8.11-generic 3.0.1 Uname: Linux 3.0.0-8-generic x86_64 Architecture: amd64 Date: Fri Aug 19 10:27:06 2011 ProcEnviron: PATH=(custom, no user) LANG=de_DE.UTF-8 SHELL=/bin/bash SourcePackage: lightdm UpgradeStatus: Upgraded to oneiric on 2011-08-12 (6 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/829247/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp

