This is likely to be a duplicate of bug #854329. If you don't have lightdm (or another DM) installed on your system and you're seeing this issue, please speak up so we know to track this as a separate bug.
This is likely to be a duplicate of bug #854329. If you don't have lightdm (or another DM) installed on your system and you're seeing this issue, please speak up so we know to track this as a separate bug.