Happened to me in 17.10. Like @fcole90 seemed to happen after unlocking my session after unsuspending my machine in the morning. The unlocking itself seemed to be stuck displaying some message about letting me continue in a few moments, but it never did. I used ctrl-alt-f6 then crtl-alt-f7 to 'wake it up', and that causes an unlock dialog to finally appear.
Happened to me in 17.10. Like @fcole90 seemed to happen after unlocking my session after unsuspending my machine in the morning. The unlocking itself seemed to be stuck displaying some message about letting me continue in a few moments, but it never did. I used ctrl-alt-f6 then crtl-alt-f7 to 'wake it up', and that causes an unlock dialog to finally appear.
Apologies for the vagueness of this!