If you haven’t used it yet then you should get to know this tool. If you have then you should be happy to know that the final 1.0 version of AuthDiag is now available at http://download.microsoft.com/download/6/c/9/6c96682c-8449-4112-a089-3b98c0035d0c/AuthDiag.msi
When you are using Windows Authentication for a web site it can be mind numbing to figure out what is causing access denied problems, especially if you aren’t a security expert. While it is an unsupported tool, it usually provides enough to get you past your access control configuration issues.
This link is to the i386, 32 bit version of the application. If you need a 64 bit version (there are different installers for AMD and Intel 64 bit chips) drop me a line and I will hunt down the URLs for you.