I had a similar problem with a desktop system.  In my case, the monitor (believe it or not) was bad.  Replaced the monitor, no prob.  Put the old monitor back in place, and the problem returned.  Tried the old monitor on a different system, and it did the same thing.  My guess is that Windows sends out a 'different type of video signal' during startup.  Of course, just a guess.
   In your case, will it start with an external monitor plugged in?  Is it new?  What model is it?  Not like I'll be able to help you, but the info will be valuable to someone who knows more than I.