Flickering fulscreen


I have some problems with enabling the fulscreen under Windows.
I’m programming under Windows with VC++.
Everything is okay. But when I want to set
to fulscreen, the screen flickeres only.
On some others computers it looks different.
So the screen is swapped between the real OGL-Screen and the old Window-screen.
On my computer I see only short lines with the real programm…

… whats going wrong in my program?