First, make sure to check the cable connections making sure they are tight. (ie. if using VGA or DVI make sure the screws are snug).
Also, have you checked the color configuration on the projector itself?
What type of graphics card is in the Laptop. You should be able to configure the color of a second display using something like Catalyst control center for ATI cards (cannot remember the NVidia equivalent)
Also, and hopefully not, it could be a port problem on the laptop or projector (VGA port going bad). Is there any way you can use a different connection type to test?