After updating to version 0.54 some rewrite rules didn't work any longer. I'm running with WP 3.5 and PHP 5.3.
The plugin conflict was with this one: http://wordpress.org/extend/plugins/wp-downloadcounter/ --> I know this is outdated somehow but since I'll find a fitting replacement I have to rely on it. So I switched back to WL v0.52 and all works again.
Maybe this will help you fix things.
Awesome plugin! Keep up the good work! I love the new translation support! ;-)
--Thanks, Dave :)