It sounds like, based on the question the external monitor might have went to lunch even thou the laptop can sense it's there.
So just to rule it out, I am sure you have already done this but just to be sure, check everything on the external screen before tackling the laptop. Since the normal video output is fine to the internal LCD, It's weird that the laptops VGA ports, the docking stations VGA port and the laptops standard port would both not work in the same way (with the docking station using another port on the bottom of the laptop) both detects the display. I hope this doesn't sound obvious or padantic or anything of the sort but just to rule everything out, have you tried another computer with the external screen?
