I've had this happen to me before too. If I remember correctly, clicking didn't stop it. I remember frantically mashing on keys and clicking buttons trying to get it to stop, and it always takes at least 15 seconds to get the right combination of keys or clicks to make it stop.
Nothing in this game has ever been as panic-inducing as this "feature" which totally takes over control of your character and prevents you from being able to cast spells or do much of anything else.
ESC might have worked. I've had freak outs in the game before as well, but they were always because of a problem with the controller. Sometimes the game doesn't like my controller if it's not powered on before the launcher is loaded. Right clicking somewhere else in the window, hitting esc and then taking the mouse cursor out of the hot zone usually corrects the problem with the click to move crap.
I'd be interested to know if anyone actually plays the game using that click to move.