I have a CVS directory in my lang directory (I have checked a full copy into CVS) this makes getAvailableLanguages() read the CVS directory as a language which fails with:
Warning: Piwik_LanguagesManager_API::require(lang/.php) [function.Piwik-LanguagesManager-API-require]: failed to open stream: No such file or directory in C:\data\Callisto\thing\UI\piwik\plugins\LanguagesManager\API.php on line 54
Screen only for .php files by changing plugins/LanguagesManager/API.php line 33 (version 0.2.31):
$languages = glob($path . "");
$languages = glob($path . ".php");
More complex fix:
Filter out directories from the list of results from glob.