Hey,
I had a problem today, when I had to assign 1 particular IP to a website on IIS 6, Windows 2003 SP2. The server itself had 2 addresses. On this website 1 of the IPs worked, the other one gave errors like “the network location cannot be reached” and wouldn’t let start the website.

The solution consists of 2 steps:
1. Open regedit and go to HKLM\SYSTEM\CurrentControlSet\Control\LSA, then add a new DWORD named DisableLoopBackCheck with value 1.
2. In Win2003 you already have that and in WinXP you have to install it additionally - support tools. Go to start-programs-support tools-cmd (not the regular cmd), alternatively you can just add the path to the system environment.
The tool you need is called httpcfg.exe and this is how you use it in this scenario:

httpcfg query iplisten

this gives you the current IPs IIS is listening to.

httpcfg set iplisten -i xxx.xxx.xxx.xxx

this adds the IP (instead of the x’s of course)
3. The secret step - reboot the server. A lot of people had problems before they realized they MUST reboot first.

Good luck!

Ozzik.