Taking a quick look (I don't have your specific 1.1.9 + SP 1.1) but lets try a stop gap measure while we continue to look.
In Load.php
// Default language directories to try.
$language_directories = array(
$settings['default_theme_dir'] . '/languages',
$settings['actual_theme_dir'] . '/languages',
);
// Default language directories to try.
$language_directories = array(
$settings['default_theme_dir'] . '/languages',
(!empty($settings['actual_theme_dir']) ? $settings['actual_theme_dir'] : $settings['default_theme_dir']) . '/languages',
);
that should get by that error, but I'm really not sure why you are seeing that. Be sure to check you theme settings in the admin panel just to make sure the directory entries look correct.