windows snapping to upper left screen

Occasionally, when I click on the icon of a running application (Calendar, Thunderbird, Firefox) in the dock, it will appear on the screen in the upper left corner instead of where I left it last. Furthermore, it will usually appear shrinked (sometimes really small), the left edge of the window will be beyond the screen border, and if I try to drag it back into the main part of the screen, it snaps right back to where it was.

The only way I've been able to recover is to quit the application and restart it. Upon restarting, it usually still has the same size problem, but I can resize and move it.

I only have one display and I just double-checked in System Preferences to be sure that the OS only thinks there is one display.

Here is a shot of what it looks like when Calendar gets stuck in the upper left corner:

That isn't the entire window (I didn't want to expose the details of my life's schedule 🙂 ) but you can see that the window extends beyone the edge of the display.

Any ideas?