cannot input password after screen has blanked

[Bruce Epper]

Mint 13 Cinnamon. After the system has been without keyboard or mouse input for 30 minutes, the screen is configured to blank, the system is never to suspend or hibernate. After system input has been idle for over an hour, moving the mouse will re-enable the display and it puts up the password box. There is no cursor in the text box and clicking on it does not put one there. The first keypress will make the screen flash blue and return to normal. No keystrokes are recorded in the input box. Can click on the Unlock button (but with nothing in the input box for the password, it just returns an error). Appears to happen as long as Cinnamon is selected as the shell. Does not appear to happen with Gnome Classic.