If you are having problems with authentication issues when trying to debug with Visual Studio on Vista then there is a fix for you.

A Visual Studio patch that fixes the Visual Studio F5 debugging of IIS7 applications on Windows Vista Home Premium and above has been released!  This patch solves the "An authentication error occurred while communicating with the web server.  Please see Help for assistance.", and "Debugging failed because integrated Windows authentication is not enabled.  Please see Help for assistance" errors, that until now had to be worked around using the instructions below.

This patch also enables customers using Windows Vista Home Premium customers to use Visual Studio F5 debugging, who were not able to use this feature at all previously because Windows Authentication was not available on Windows Vista Home Premium.

Mike Volodarsky's ServerSide : Fix problems with Visual Studio F5 debugging of ASP.NET applications on IIS7 Vista

ttfn

David