Pointer Throws Itself Randomly During Game

Its been a while now that in game my mouse pointer throws itself randomly during the game. This happens ONLY when i play league. I've tried different mouses, using different ports, repairing the client, and shaking the mouse in frustrating manner after it throws itself. This problem has been the cause of many loses for me, it is extremely frustrating PLEASE HEEEEELP! Thanks in advance.