Fullscreen but not fullscreen

I Will try to explain. My mediacenter is always on when i switch on the tv and reciever i get 90% of the time this screen. I have to restart my pc to get it fullscreen again. Xbmc is launched with xbmclauncher on Windows 8 ass shel. Xbmc setting show stil fullscreen and my desktop isn't shown so it looks like xbmc is still fullscreen butt the picture is cornerd. Hope somebody can understand this ;-)



It looks like this.

Thanks to any one that can help.