Tech note FS1459
Configuring the FlashStats CGI as a Web Service Extension (IIS 6).
When you run FlashStats on IIS 6, you need to configure IIS 6 to allow the FlashStats.exe CGI to run. This is done by defining a "Web Service Extension" in the IIS Manager utility.
To do this, open the Internet Information Services Manager (Start / Programs / Administrative Tools). Expand the desired computer (usually the local machine). Select the Web Service Extensions node, then add an Allow entry pointing to the FlashStats.exe file.
More detailed instructions on adding a web service extension are available from the Microsoft web site.