Just recently this situation occurred. I can see that the 2nd monitor is active, but when I switch to it, nothing appears on any monitor. The window seems to be "virtually minimized", meaning that the the width is nil and the height is full. If I do a mouse-over on the taskbar (client side), I can maximize the screen. I can also switch to single monitor mode and switch between monitors. I cannot resize the monitor to fit any of my monitors.