Screen is frozen but game is still running

This issue started about a month ago when I alt-tabbed out of league to play some music, when i tabbed back in the screen was frozen except for the mouse. I could tell the game was still running because sound was still playing and I was hearing my characters voicelines when i move and ability sounds just fine. alt tabbing in and out of the game seems to make the screen unfrozen for about half a second then freezes again. Occasionally an alt tab out and in will fix the issue for the remainder of the game. I've tried reinstalling the game and even reinstalling windows 10, but the same issue is occuring even tho i've never had this issue playing league for years.