Bug Report

So my friend is trying to play league, but he can't. He has this weird glitch with his game but I have know idea how to fix it. It's hard to explain but I will try. So as you probably know there is a small white box on the map while in game, well my friend has 2 on his map. He has 2 and it switches between the 2 constantly but it doesn't only affect the game screen. The entire screen is glitching out, it's hard to see the map, your champion stats, your score and also while this glitch is going on he can't access the shop, attack a champion or minion, and can't even use his abilities. I have no idea how to fix this, please help. Thanks