HELP !!!

I have SQL2000 running on my home PC using Windows 2000 Professional. My
web site has some XML files that run sql queries to retrieve and display
the data as a wweb page. Everything works if I use my web site on my local
computer( at home). I can access my web site from my PC at work but when
I try to bring up a page that is generated as a result of XML, I get a "not
authorized to view this page" msg. When I execute the same function at home
I get a log-in screen and when I enter my windows ID and password it works
fine. I have the virtual directories set up using "Windows authentication"
as security.

Any help would be appreciated...thanks