My Dell D620 Does not work with our presentation system projector

We use mostly Dells where I work and the Dell D620 laptop with the intel video card does not work with our Presentation system projector. However other Dells do (use a d400 with this system regualarly with no problem). I talked with the company that has renovated our system and they said that it is probably the laptop looking on pin 9 of the vga connector for an ID bit, which is not present as the system is only connected with a 5 wire VGA connector.
These same laptops will work with stand alone projectors or flat screen monitors plugged into the same VGA port, so it is not a port problem.
Any suggestions on how to over come this difficulty?
Thanks.