Possible bug in the rich text editor
This is not a bug in the rich text editor -- but is the way a wiki interprets links.
If you want to the "www.ahri.com.au" to display as the link,
First type out the letters "www.ahri.com.au" in the edit window, highlight these letters with your mouse, then click on the link button and enter the full url.
Then you will get:
Hope this helps -- the way you are doing this at the moment is creating a new page in WikiEducator which has an identical name to the url :-).
This tutorial will provide more information.