I have my Ubuntu 12 desktop set to lock after a time period-- this works fine, but when I go to unlock it sometimes (usually only after leaving it locked overnight) won't come out of the locked state-- the lock dialog goes away but it still shows the image from the locked screen (usually a picture from variety, which I use as a background switcher).
I can Ctrl-Alt-F1 into a command prompt, and the processes seem to be fine, so I think the system is fine, it's just the lock app (or whatever it is) that might be screwed up.
How can I diagnose this? Is there a
kill command I can issue from the command prompt to disable the lock view?