Unable to access any web services in the _vti_bin folder from SharePoint web server

We have an internal portal hosted on a SharePoint web server. There is a separate server for indexing the portal content. I have a custom web application that invokes the SharePoint search web service and it works fine on my development machine. However when I deploy it to the SharePoint web server, I get this message

"The request failed with HTTP status 401: Unauthorized."

If I try to access the web service from the browser (http:///_vti_bin/search.asmx) from the production serv开发者_StackOverflower, I get the 401 page. But it works fine from the any other machine. This is an internal portal. Any help would be deeply appreciated.

Thank you.

If you get the 401 error when browsing any Sharepoint page from the local machine, try checking out this article or this article (both from support.microsoft.com)

It describes how to disable/work around the loopback check introduced in windows 2003 sp1.