Check php.ini file located in the PHP 5 installation folder (for example, C:\Program Files\Parallels\Plesk\Additional\PleskPHP5\php.ini) or in the the C:\WINDOWS folders on the system disk.
Copy the system php.ini to httpdocs of the domain and change register_globals to on in this file to have modification for 1 domain. Make sure that php is set to run as cgi and not isapi; to use a custom php.ini