You are running your web server on a Domain controller.
See KB
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q315158Change your Machine.config like the article says. This started with the RTM version. It didn't happen with the Beta.
>Hi Guys,
>I'm trying to get my first webservice running with the hello world example. and I'm getting an Error in the browser the server application you are running is unavailable.
>In the Application Event viewer I get this error
>
>[aspnet_wp.exe could not be launched because the username and/or password supplied in the processModel section of the config file are invalid.]
>
>I am running Windows 2000 Advanced Server with the Vs.net which was just released(not beta)
>
>regards,