Thanks for your bug report. Do you have any interesting messages in
/var/log/gdm ?
** Tags removed: edgy gdm
** Changed in: gdm (Ubuntu)
Importance: Undecided => Medium
Assignee: (unassigned) => Ubuntu Desktop Bugs
Status: Unconfirmed => Needs Info
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Gdm don't save session settings
https://launchpad.net/bugs/69419