Stop timer

I have this code to time out my Flash movie and go to a URL

stop();

var jumpTimer:Timer = new Timer(5000);

jumpTimer.addEventListener( TimerEvent.TIMER, jump);

function jump(event:TimerEvent):void {
    navigateToURL(new URLRequest("http://www.yahoo.com"));
}

jumpTimer.start();

The only problem is that it opens a new URL window every five seconds. How can I get it to time out after 5 seconds, go to the URL and then stop before it opens another URL window?

Thanks!