When I startup Firefox the window flashes on screen but will not open. The window is listed under the "Window" menu but cannot be displayed. If I open a new window and then select the old window, I still do not see the old window but it is active in the "Window" menu. When I "close" the old window from the "File" menu I will see a new window in the "Window" menu (close all tabs?), which I assume is the dialogue box and also not visible. If I hit return with the dialogue box active, both the old window and the dialogue box close.

I have done both a Refresh and a Reinstall separately of Firefox with no change in behavior. I have tried restarting Firefox with and without the "restore previous session" selected in preferences with no change in behavior. I am at a loss with where I go from here. My current workaround is fine but a pain and obviously I cannot recover my previous session with this issue. What else can I try to clear this issue?