change the permissions for the gallery folder and all folders and files under it to 755.
then in the admin_gallery/common/properties.php file, edit the following lines:
$GLOBALS['permissions'] = array(
'dir' => 0777,
'file' => 0666
);
to:
$GLOBALS['permissions'] = array(
'dir' => 0755,
'file' => 0755
);