This is what the Ubuntu bug webpage says the package is when the bug happens at the login screen.
** Package changed: ubuntu => lightdm (Ubuntu) -- 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/1009986 Title: Ubuntu crashes at login Status in “lightdm” package in Ubuntu: New Bug description: Ubuntu crashes immediately after logging in and reverts to the login page. Distribution: Precise Pangolin 12.04 Kern.log attached To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/1009986/+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

