OSDev.org

I downloaded something like that to play a game
what needs OGL to start. It worked BUT now is my
screen so big, that it's been halfed in two and
I can scroll my screen with the mouse...

Can someone help me, or is my english SO BAD?

Some video drivers have a feature where you can have a 'virtual' desktop larger than the screen itself. You can turn this off in the display properties.