When I click a custom menu link, how do I make it update the URL in the browser to the external link? Thanks.
I believe it's because you're using a frame. The url is changing within the frame itself but it can't reflect it to the base site. You'll have to remove the frame from the site in order to have the url change for you. In fact, I really don't see why you have a frame anyway because if I right click (using FF) and select view only this frame...the site works exactly the same and the URL changes.
Unless I'm missing something, I believe that's your fix. Let me know how it goes.