ManaWave

Hey!
I installed mw2 on my school laptop wich is useing windows 7.
The game runs fine except that the game tabs by itself. The "win tab key" is not broken or anything like that, this is the only game its happening to. It just tabs down and after it just comes up again... its veeery annoying.Anyone who had this problem before? or ideas how to solve this. By the way is there someway you can lock a window like mw2 so it cant be tabbed down or something like that ?
/thanks for fast answers