Gameplay Glitches

Now, before I write anything else, I wanted to say that this certain bug ONLY happens when I play League. I've tried all my other applications and everything runs fine. Whenever I hit certain buttons, such as tab (to see the K/D/A spread), escape (to exit a game when the bug occurs), or P to open the shop, the entire screen goes into a panic and flashes and becomes really glitchy. I've read other comments where other players have the same problems, how do I fix this?