Unable to view ext website that is hosted on internal DMZ

We are running a Win 2k3 domain, the DC and DNS are on the same box, firewalled from the internet via a sonicwall pro 2040, users browse the web via an ISA 2000 box. I have set up an internal webserver in the sonicwalls dmz with public ip 62.172.177.71 which can be accessed from the outside world without any problems. When clients try to access the website I get an 11004 – host not found error and reference to the ISA.

I’ve created a DNZ zone on the DNS server for the public address and entered the public IP. When I run an nslookup on my network it does find the route through to the site but I still cannot access the www. site from my internal LAN.

Any ideas would be greatly appreciated.

Regards