Hello,
I had a windows forms application calling web services and I got the following errors during the execution of the winform application.
System.Web.Services
The request failed with HTTP status 401: Unauthorized
I realized later that when I enable the anonymous access and added the computername\Users group, SYSTEM user and ASP.NET Machine Account (ASPNET) user with read permissions in the NTFS security ACL settings of the web service application the problem was solved.