phpinfo() shows MySQL from CMD line, but not in browser

Configuration:
Windows 2000 Server
IIS 5.0 PHP set to run with the isapi.dll
PHP 5.0.4
MySQL 4.1

IUSR_servername has Read, Execute access to \php and \ext


Lines from php.ini

; Directory in which the loadable extensions (modules) reside.
extension_dir ="./ext/"

extension=php_mysql.dll is uncommented


Still, trying to load phpmyadmin gives

cannot load mysql extension;
please check PHP configuration
Documentation


phpinfo() run from a CMD prompt shows MySQL support
phpinfo() run from a script in IIS does not

Can someone point me to what I am missing?

Thanks.

Scott