Asp – Unable to start debugging on the Web Server. Visual Studio 2008

I am running visual studio 2008 on vista business 64-bit. I am getting the following exception when I try to debug against IIS.

"Unable to start debugging on the web server. The object identifier does not represent a valid object".

IIS and Visual Studio are on the same box.

I've tried adding Windows Authentication but no luck (my app requires forms authentication, fyi).

Any thoughts? I have a binding on the Web Site. The IIS app is a Web SIte not a virtual directly.

Thanks!