OS X :: MB Air Display Won't Work - How To Fix It

i have a problem with a macbook air rev. a that was just given to me. it had the broken hinge/LVDS cable, along with the lcd. I just bought all these parts new and installed them, along with a clean install of snow leopard. The problem is that the laptop will boot up until the blue screen and then load the desktop backround picture, but will then freeze up and do nothing. ive tried with the snow leopard disc in (except the image on a usb drive), in safe mode, and every other button combo at startup, and the same thing happens everytime. But for some reason if i unplug the LVDS cable from either end the computer will boot up just fine(plugged into an external monitor).