Comment 26 for bug 1311403

This happens sporadically on my 2013 Dell XPS-15 (same model Mark Shuttleworth uses... just sayin' ;)

For me, the passowrd text box often just doesn't show up at all.... the rest of the UI is there, but not the text box.

Sometimes I can click on guest session from the gear menu to get it back, but sometimes there is no gear menu, and I have to hard reset (maybe there's some other way to cancel out of the lock screen, but I don't know it).