Can't open web site

This just isn't my day.

I have VS.Net loaded on a W2003 server running IIS6 and a functioning
ASP.Net web site. I load VS.Net on the server and tell it to Open a
web site on that server. I enter the URL;
http://mysite.mydomain.com. It promts me for a username and password.

I've entered the local administrator credentials, the domain
credentials, my user credentials and every time the username/password
box just keeps popping up.

I have that exact project open on a remote workstation. It accepts
the username/password I enter., I can edit the website permissions
and both the local and domain administrator accounts are in there.

Why can't I open this on the server? Why can I open it from a remote
workstation?

Thanks!