Installation issue with PHP 5.3.1

I am about to throw something very expensive through a large window right now. Here's the issue: PHP version: 5.3.1 Server: IIS 6 OS: Windows XP SP2 I had PHP running fine on my development machine for months, but then I had to write a script that allows users to upload files to my site. Due to the ridiculous security settings for IIS, I got frustrated and decided to switch to Apache 2.2.14. COULD NOT get PHP 5.3.1 to work with Apache (the normal php.ini lines worked fine, except for PHPIniDir - this caused Apache to crash on startup. If it was left uncommented, it worked fine), so I'm trying to switch back to IIS. I've completely uninstalled PHP from my machine & removed any old files. When re-installing using the msi, I get the following error message: "Error trying to find the nodes containing scriptmaps :GetDataPaths Failed. You will need to manually configure the web server." I then manually configure the server to use FastCGI, according to the instructions on the PHP website. After restarting IIS, I navigate to the test page for my site. Instead of displaying the page, my browser downloads the page as a file. Does anyone have a clue what's going on here? -Matt