I just installed fs9 for the first time last night.I ran it "out of the box" first and everything was OK.Full screen to window mode and back to full screen etc.Then I installed latest ver of FS Nav,ver. 3.06 fuipc,advdisplay,and RC3.1.When I went from full screen to windows mode so I could run RC that's when it went black going back to full screen.I haven't been monitoring this problem in the forums because this is my first time using FS9.I think I tried the alt key but I'm not sure.I am going to do a step by step reinstall of everything tonight with ver 3.07.I didn't run fs9 enough before installing the extras to know if the problem happened only occaisonally. At least I know now that it's just not something I did wrong.Thanks,Ron