Black screen when i print screen in-game.

I need some help i get a black when ever i do a print screen in games. I have an Ati 4870 i did some research and found that i need disable hardware acceleration. But the problem is that i can't even access it, The change settings tab in troubleshoot is ghosted out so i can't disable it. Any help plz?

Im using Win7 BTW.

Click Properties on the game icon, then on the compatibility tab check - Disable desktop composition and run the game. It disables the win7 aero theme when you run the game which will allow you to capture your screen ;)