Посмотрите пожалуйста:
http://forums.aspfree.com/net-development-11/the-request-failed-with-http-status-401-unauthorized-11744.html
Похоже что там есть решение Вашей проблемы:
You have two choices:
1. Enable anonymous access.
You can do this by:
a. In Administrative Tools double click on IIS.
b. Right click on the Web Service you have developed.
c. Click on Properties.
d. Click on Directory Security Tab.
e. In Authontication & Security Box, click on Edit Button.
f. Click on Enable anonymous access.
2. Authenticate yourself to the Web Service.
I'm assuming that you added a reference to the Web Service in your
Windows Application, Windows Service, Web Application or Console
Application. Also, I'll assume that the name of the Web Service is WS.
WS.Service1 svc = new WS.service1();
svc.Credentials = new System.Net.NetworkCredential("myUserId",
"myPassword");
svc.PreAuthenticate = true;
try{int sum = svc.Sum(1, 1);}catch(Exception ex){Console.WriteLine(
ex.Message)}
1. Hope this helps.
Владимир Тришин
http://programmer-kharkov.com