Scott Pinkston sent me a note this weekend about a problem he ran into:
I had a page that set a form variable called path. The action page then used the path variable to determine which table to use. I just used #path# in the code instead of #form.path#. Under IIS this worked, under apache it threw an error. I could not figure it out until I decided to look at the value of path. Apache returned the following for #path#:C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\system32\WBEM;C:\Program Files\ATI Technologies\ATI Control Panel;C:\Program Files\Microsoft SQL Server\80\Tools\Binn;C:\Program Files\Microsoft SQL Server\90\Tools\binn;C:\Program Files\Microsoft SQL Server\90\DTS\Binn;C:\Program Files\Microsoft SQL Server\90\Tools\Binn\VSShell\Common7\IDE\
IIS returned the value of the form.path variable. Under Apache, once I changed it to form.path things worked.
Yet another good reason to use the full scope when referencing variables, and thanks to Scott for sharing. This is probably also a good place to remind folks that CGI variables change between web servers as well. If you plan on running a site on IIS, or Apache, it is a real good idea to make sure your dev environment uses the same web server.