Thanks for your bug report. Do /var/log/Xorg.*.log or
/var/log/gdm/:0.log say anything interesting about the case?
** Changed in: gdm (Ubuntu)
Importance: Untriaged => Medium
Assignee: (unassigned) => Ubuntu Desktop Bugs
Status: Unconfirmed => Needs Info
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gdm fails to create session
https://launchpad.net/bugs/51233