This one really make me confused.
The open_basedir was set to the directory app needs, and it just gave me the error message.
PHP Warning: file_exists(): open_basedir restriction in effect. File(C:\inetpub\wwwroot\ATI\WP/wp-content/plugins/post-new.php?post_type=page) is not within the allowed path(s): (C:\inetpub\wwwroot\ATI\WP;C:\inetpub\temp) in C:\inetpub\wwwroot\ATI\WP\wp-content\plugins\ozh-admin-drop-down-menu\inc\core.php on line 129
What can I do to deal with it?