That staging window is now everywhere... Okey, i have found where it came from, it was from one of my satellites orbiting Kerbin. I was wondering why it was stationary in space, while my other satellites were moving fine in their orbits.. So i loaded into it, and its engine was burning when it loaded in... well turned it of and fixed the orbit. After that the stage window was still stuck. After loading into another satellite, it got rid of the broken stage window !. I can finally do staging again in the VAB!