This might have been asked, or I am doing something wrong but...
Can you just put an ip address into the adress bar. I am testing something utilizing a local webserver, that the script on your server that resolves DNS does not know about.
If you run a local DNS-Server in your LAN, (ie on Win/AD-Server), can´t you add a DNS-A-Record to point to this local IP-address ?
(or is Stuart´s Browser using a "fixed" DNS-Server to resolve requests)