Did you ever notice that if you try to navigateToURL() from inside Flash in Safari it will refresh the Flash on the page? Here is a quick work around

You need to setup a JavaScript function that uses the DOM to fidget w/ the window.location.hash. It looks something like this;

function mapAnchor(anchor)
{
window.location.hash = anchor;
}

Then from ActionScript setup a navigateToURL() like this;

var _anchorlink:URLRequest = new URLRequest("javascript:mapAnchor('"+anchorname+"')");

where anchorname is your anchor.