PHP 5 - Apache2 - mysqli class not found

I have an install of PHP 5 on Windows 2003 Server with Apache 2 and when I reference mysqli in my php code, I get an error that the mysqli class is not found. I looked at the php.ini file and I added a line for php_mysqli in the extensions section and I edited the extension_dir directive to point to c:\php\ext folder (I used "/php/ext" as the value assigned to the directive. I made sure that the c:\php\ext folder actually had a file called php_mysqli.dll, which it did. No I can't start my Apache server. I had done a default install of both Apache 2 and PHP 5. Any ideas as to how I can get the mysqli class identified and allow my Apache server to start. Thanks, David