uncontrollable mouse *on one account only*

So I have two accounts. On one of them, the mouse works perfectly, as it always has. On the other account, the mouse is uncontrollable and vibrates rapidly or jerks around and is basically uncontrollable. Anyone have any idea why this happens? I am logging on to both accounts from the same computer, and I know the settings are local to the computer, which makes it even weirder. Also i'm on Mac