my micrsoft combat flight simulator minimized now

anyone have any idea how to fix this?it didn't use to happen.i can fix it until i power down if i open up taskmanager and click switch to (windows xp by the way) and if i start up the flight sim and hit Alt then it will go to full screen otherwise it stays at half and if i don't make it go to half it won't maximiza the darn thing. idk what the problem is it never used to do this before.