"NEGATIVE" picture? (inverted colors)

Hey all,

OK, just set up a "home build" projector with a tft screen on top of a classroom projector, but the image is coming up as a negative photo would?

Please, i have on idea how to correct this, any ideas?

btw, its hooked up to my pc, and if i go to accessories/ accessability/ magnifier, and select "invert", i get a small part (the magnified part) of the screen in its normal colors.

Many thanks all,

OFFICA