I have abroken laptop screen. Machine is HP and running on Vista. I'm trying to connect to an external monitor. If I use the fn f4 route it doesn't work. I can't click through the proces on the screen to change monitors because I can't see anything on it. If I start in safe mode I have no problem, the fn f4 works and I can toggle on and off the external monitor. It doesn't make sense that it works in safe mode and not normal mode. Can't do what I need to in Safe mode...it doesn't give me the options. I've tried changing resolution but this makes no difference to the problem.
If you screen works in safe mode - then you do not have a hardware problem. It's software based. if you tried changing the screen resolution and that didn't fix the problem. then the next thing to try is the Video chip drivers. Go into device manager and roll back the drivers for the video adapter. You might have installed the wrong video drivers.