I also have three monitors of various sizes and orientations. I observe exactly the same problem. The problem is general: it occurs with other applications that pop open a window. The applications open the pop-up in a part of the large virtual rectangular screen that is just outside of the viewing space shown by the existing three monitors.The above solution will work but here's a cleaner solution (at least in Windows 7):If you don't see a pop-up window, before you click on any screen, press Windows-left-arrow or Windows-right-arrow. This will move the pop-up into one of your three windows.