Things that go download in the night....

I was testing a secured website directory running on my local machine.

When accessing the resource as "http://www.mywebaddress.com" instead of "http://localhost". The Windows Integrated Authentication login popup would appear three times. I would type in the correct user name and password. But every time, I would be denied access. Eventually receiving the message:

HTTP 401.1 - Unauthorized: Logon Failed

I had a related problem while using Windows Server 2003 SP1.

Error while trying to run project: Unable to start debugging on the web server. You do not have permissions to debug the server.

Verify that you are a member of the 'Debugger Users' group on the server. NOTE: I AM the administrator on this machine, and have made sure that I had the 'Debugger Users' role..

After much digging around I finally found, the crux of the problem is a recent security patch that came down with XP SP2 and W2K3 SP1. It is called loopback security check, and you can get around it by following the instructions in the Microsoft Knowledgebase.