XML.load - specifying port in the path


I have stumbled across a problem when loading XML via an external address using Firefox. Consider the following code:

var my_xml:XML = new XML();
my_xml.ignoreWhite = true;
my_xml.onLoad = function(success:Boolean) {

This works fine in all browsers. However, if I modify the target path to include a port number (even the default port 80), it doesn’t work in Firefox. It works normally in IE.

So the path could be: “http://www.mydomain.com:80/test.xml”, and it won’t work in Firefox. No response.

Does anyone have any suggestions how to overcome this problem in Firefox? I need to be able to specify different ports (I just used port 80 as an example).