Has to be a fear effect or something. If it happens out of combat then, eh, it's beta. One thing you can do is down in the right lower corner you can click that little yellow arrow poking out of the right screen. It will pull out what I call your combat log. It explains everything that goes on in your screen in a neat little box. Ok, so not so neat, which is why they hide it. But it's there, it'll tell you everything that is happening or has happened. Check it out, it'll help.
