External monitor

[doc79]

I've got Vaio VGN-FZ11SR.

I have plugged in an external monitor cable, but there is no image on the external monitor! No image from the very beginning - just after I turn my Vaio on.
Fn+F7 has not helped.

And the very strange thing is that the external monitor has recently functioned properly with my Vaio (before I reinstalled Vista, but I don't think that is the reason).