This could be something silly, like you haven't adjusted your monitor's brightness and contrast correctly. What do you think those tiny little button are for?!
However, if you're brighter than that and you've been through the ropes of installing the latest drivers for your video, checking your Windows display property settings and playing around with OFP's own brightness and gamma video settings, then maybe it's just your monitor. I've experienced this on a old IBM P92 17 inch model.
There's still hope, though. You can try out a software product, called Powerstrip, that lets you tweak your display hardware to the max! You download the latest version from Powerstrip's developers, Entech Taiwan.