UNC, GetFolder & Windows Authentication

I have an IIS 6 server on Windows 2003 running in an AD domain attempting to
enumerate the files on another Windows 2003 server on the same domain. The
code and UNC path are sound as it works if I set anonymous access and enter
domain credentials in the page properties but if I check "Integrated Windows
Authentication" it gives a "Path not found" 800a004c error in the browser.
The IIS logs report a 500 0 0 status but it does show that it attempts to use
the end user's credentials as you can see them in the logs. The IIS server
is set for "Trust this computer (for Kerberos only)" but the the other server
is not. The user running the page has full permissions to the remote UNC and
can access it outside the web page.

The two significant lines in the classic ASP page (with the server, share &
folder names replaced) are:

spmsmmpath="\\server\share\folder\"
SET ofolder=ofs.GetFolder(spmsmmpath)

What am I missing? Does the file server need to be trsuted too? Do I need
to use a MapPath command or am I using the wrong slashes? Remmeber the code
works as is if I pass literal credentials.