What webserver are you using?
I remember having this error when we originally configured the IIS server.
- Properties for Domain/Web Directory
- "Home Directory" tab
- "Configuration" button
Your entry for .php should read as follows:
drive:\path\php.exe %s %s
Yes, two "%s" and spaces between them and the path to the PHP CGI.
Hope this helps,
-Sean
ps. If you're using a different webserver, let me know and we'll see what we can do.