[CLIENT] Um, Alt+Tab won't work?

Note: I have just recently upgraded to Windows 10

During game, if there is no other window available, you can't alt+tab to the desktop. However if you hold it down, it will flash between the desktop and the game. What I assume is happening, is that League takes priority over the desktop. When there is another window open, you can alt+tab to it, but you can't really go the desktop (except by pressing windowskey+D). I have tried pressing windowskey+D in game, but that just caused me to heal and didn't do anything. I'm not sure if this is just a problem only I have, or if this is a global problem with Windows 10. Plz help!