When I use my second monitor for some of the windows, like the task groups window, the windows will open up 'off-screen' after I close them on the second monitor. My second monitor is positioned on the upper left corner of the main monitor in the Windows display settings, this is to avoid my mouse 'accidentally getting lost' on the other screen. So, when I move an window, like the task groups window, to the second monitor and close it there and open it again, it will appear 'off-screen' 'below' the second monitor. See the image below for a visual explanation. The only way to get the 'off-screen' window back on-screen is to use the move function on the taskbar and then move the window with arrow keys till Its on-screen enough to be moved with the mouse. While not game-breaking, its still annoying.
[attachment=0:27szheao]Monitors.jpg[/attachment:27szheao]