PHP, IIS, and multiple web sites

I've installed PHP on IIS 5.0 and it does work fine--for my default web page. However, I have a second web page on the server, which is located on a separate hard drive, and PHP does not work for that one. All I get back is a blank page with the simple "Hello World" php script, although the exact same script works if I run it from the default web site located on the same hard drive. I've changed the doc_root setting in the ini file, but that didn't do a thing. I'm running on Windows 2000 Server, with pretty up-to-date patches and service packs, IIS 5.0, and PHP 4.1.2. I thought I had seen something in the docs about PHP needing to be on the same drive as the web page, but I can't locate it. As it is, PHP is on C:, as is the default web page, but the one for which I need PHP is on D:. Is this the problem? Mark Payton