MX2004 help: pausing a movieclip that's moving via actionscript

stupid question, I know, but for some reason I can’t get it to work right. any help is appreciated.

here’s what I have going on so far–I have a movieclip that’s acting as a continuously scrolling text field, and want it to stop scrolling onMouseDown.

here’s my code right now:

onClipEvent (enterFrame) {
	location = this._y;
	var i;
	i = -1;
	if (this._y<-700) {
		this._y = 900;
	else {
		this._y = location+i++;