Infocus 4805: no image from GeForce 8600 using S-video to component adapter cable

I have a ceiling mounted InFocus 4805 projector with component cables AND 4-pin S-video cable installed inside walls.  I get perfect images from my XBOX using Hires output to component and also S-video from my DVD player.  I want to connect my computer through the same selector switch box as the other two devices to the projector using either s-video OR component connections but neither work with any combination of conversion cables:  I have a GeForce 8600 graphics card and have tried direct s-video straight cable, vga to s-video, HD to s-video, 7-pin S-video to component, vga to component and HD to component.  I get no image and the projector only says "searching" and sometimes "out of range"  It WILL work if I connect the computer directly to the projector via HD cable but I want to use the cables that have been pulled through my attic.  This is a complete mystery to me as I have tried everything except buying a converter box for VGA to component but that would lower the resolution and only a last resort.  I have also eliminated the switch box as a possible problem by using direct s-video to component and direct s-video.  I have setup the Invidia software for dual display, and it shows the Samsung monitor and TV as correctly chosen.  I also set up to clone the image to both devices and and check the box for "rigorous" detection of devices.  Nothing works.  PLEASE HELP !!