PHP Warning: Failed opening...

I'm trying to install PHPBB (http://www.phpbb.com) on top of a new PHP 4.2.2 install on a Windows 2000 server (up to date). Truthfully, I don't know if this is a PHP problem or PHPBB problem but, nonetheless, it's annoying the heck out of me. Anyway, PHP seems to be working (running phpinfo() returns results that look normal). However, when I fire up my phpbb web site, I get the following: PHP Warning: Failed opening './extension.inc' for inclusion (include_path='.;c:\php4\pear') in E:\InetPub\WWW_webpath\forums\index.php on line 25 PHP Notice: Undefined variable: phpEx in E:\InetPub\WWW_webpath\forums\index.php on line 26 PHP Warning: Failed opening './common.' for inclusion (include_path='.;c:\php4\pear') in E:\InetPub\WWW_webpath\forums\index.php on line 26 PHP Fatal error: Call to undefined function: session_pagestart() in E:\InetPub\WWW_webpath\forums\index.php on line 31 Poking around on deja, I tried changing the include_path directive in php.ini to point to the php\pear directory to no avail---same error, different path. Now, I know that PHPBB will work on a Windows server running PHP 4.2 because I've set it up on my web providers web server (PHP was already set up by them). It worked fine. Unfortunately, I don't have access to go poking around to see the differences. Phpinfo() returns similar results on that server and the one I'm trying to set up. Any help is greatly appreciated. Thanks -Roger