which causes problems when enabling exif extension because mbstring has to be loaded first.
(http://www.php.net/manual/en/exif.installation.php - Windows users must enable both the php_mbstring.dll and php_exif.dll DLL's in php.ini. The php_mbstring.dll DLL must be loaded before the php_exif.dll DLL so adjust your php.ini accordingly.)
Could you please fix the order in default php.ini?