Unable to download XLS file from IIS6

Hi All:

I've developed a small ASP.Net app that builds an Excel sheet and
presents a link to the user. I'm able to get it to work on my
development box (XP) but when I load onto the Win03 Server, I'm not
able to download the file. The typical 'Do you want to Open or Save
this file?" dialog comes up, however when I click Save, it give me an
error Cannot download - The requested site is either unavailable or
cannot be found"

When I browse to the Virtual folder in IIS Admin, I get the same
results. So I think it's some config setting that I'm overlooking.
Any help would be greatly appreciated.

-Bob