Windows Vista Must Restart In Order To Connect an External Display
It was a big surprise for me, but yes: if you want to e.g. connect a video
projector to your Vista machine, you have to restart the machine.
For a long time I thought it was only a Solaris issue. With some laptops
you just need to restart your X server session (i.e. logout/login).
Recently I have heard from one of my colleague, who was giving a presentation
(on the last Wednesday) he was not able to use the projector at all (he unfortunately
did not try to restart his machine).
Then I tried to connect an external LCD to one of our laptops which is running on Vista
and have succeeded only after restarting the machine.