Comment 1 for bug 762058

I just had this happen again. The only similarity may be having Thunderbird open, not sure if I have had it open during each of these occurrences. Perhaps the new email notification window in Thunderbird messed up the window focus.

The only other commonality seems to be that you need to wait for a long while. It doesn't seem to happen after quick locks/unlocks. Perhaps that means the bug is in power saving mode if this is only happening after it puts the monitor to sleep.