My laptop does not recognize any projector

I got a dell Studio 1537 , and since I installed Windows Seven 7 64 bits I haven't been able to connect my laptop to any projector...  I have tried to press Start + P and tried all the opts that pop up  and nothing, I also tried to press Fn+F8  (that is the key with the little laptop and monitor) and the screenflashes but the projectors dont recognize the laptop though.

Please if any of you could help me I'd be thankful