I have this problem on at least 2 computers, but cannot find any answers. If Firefox is opened already, and I launch another instance of Firefox (from a shortcut on my ribbon), then the window will appear but be a translucent blue. I cannot do anything but close the window. However, if I go to my first instance of Firefox, and select "New Window", then it CAN open a new window that works. Somehow, Firefox goes into a mode where you cannot launch a new instance unless it is only from the existing instance. I get the same problem on my home computer (a desktop) as my work computer (a laptop). It is not consistent, but happens sometimes on the 3, 4, 5 or higher instance. But it does happen on two computers. I've uninstalled and reinstalled Firefox, but eventually it comes back again. Bot computers running Windows 7. Any ideas?