PHP 5.3.5 installation on IIS7 (Win Web Server 2008 R2) generating 500 Internal Server Errors

I'm trying to install PHP 5.3.5 on Windows Web Server 2008 R2. I've installed PHP plenty of times in the past and never had an issue with it, but this is my first time installing it on a Windows 2008 system. When my first attempt failed (I kept getting a 500 Internal Server Error on a PHP file that just contained <?php phpinfo(); ?>), I reverted the machine back to its post-OS-install state and tried again by following the instructions at http://learn.iis.net/page.aspx/246/using-fastcgi-to-host-php-applications-on-iis-7/ and http://www.php.net/manual/en/install.windows.iis7.php

Same problem. After completing the installation process as described on these pages, the phpinfo() file that I attempt to open in my browser throws a 500 Internal Server Error. If I test it from the command-line by running php-cgi.exe on my test PHP file, it works fine there. Also, if I just test a file that contains an echo statement in it, that works in the browser without generating a 500 error. Why the hell would phpinfo() be causing a 500 error?

I took it a step further and dumped the result into an HTML file:

php-cgi.exe c:\inetpub\webpublic\phpi.php > c:\inetpub\webpublic\phpi.html

It just generates a warning:

PHP Warning:  phpinfo(): It is not safe to rely on the system's timezone setting
s. You are *required* to use the date.timezone setting or the date_default_timez
one_set() function. In case you used any of those methods and you are still gett
ing this warning, you most likely misspelled the timezone identifier. We selecte
d 'America/New_York' for '-4.0/DST' instead in C:\inetpub\webpublic\pi.php o
n line 2

Other than that, the generated HTML file is fine.

I'm using the non thread-safe version of 5.3.5:

C:\PHP>php -v
PHP 5.3.5 (cli) (built: Jan  5 2011 20:36:18)
Copyright (c) 1997-2010 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies

Any ideas? I'm about to kick this server through a wall. :)