Networks Not authorised to view, 2k3 web server directory browsing a remote share.

I hope the title was just vaigue enough to work, its hard to give a good idea of my problem in a title. so that will have to do.
What i have is a 2k3 server running my website and i also want access to my folders and shares on my file server. (seperate box) So i set up another site with directory browsin enabled and set it to \\server\share and disabled any anonoymous access. Then i get:

HTTP Error 401.3 - Unauthorized: Access is denied due to an ACL set on the requested resource.
Internet Information Services (IIS)

however if i change the path to my website share \\server\share\site where the domain user "web" has access (internet access for anyone usin the site) and enable the anonymous access it works and i get my website directory. But if i remove anonymous access and put in the username and password for the web user i get the error!
Any ideas?