IIS 7 401 Error - Unauthorized: Access is denied due to invalid credentials

I thought this one was going to drive me crazy. I set up a web application on a Windows Server 2008 using IIS 7 and ASP.NET 4. I set it up to use Window Authentication but I just kept getting a 401 error - which made no sense. Everything on the network was windows-based. There should have been no problem finding my credentials. I was finally lucky enough to come across this on the web:

http://social.technet.microsoft.com/Forums/en-US/winserversecurity/thread/c9239a89-fbee-4adc-b72f-7a6a9648331f/

Below are the steps to stop this from happening:

• Open IIS and select the website that is causing the 401
• Open the "Authentication" property under the "IIS" header
• Click the "Windows Authentication" item and click "Providers"
• The issue should be that Negotiate is above NTLM. Move the NTLM to the top spot and that should fix it.