I've just installed (and uninstalled due to incompatibility with my theme) the Nexgen Gallery Voting plugin. The plugin is great otherwise and I'm sorry I'm not able to use it with my theme.
Upon uninstall the posts with galleries just shown one picture and the page was broken. I just then remembered I have to delete the
<?php echo nggv_imageVoteForm($image->pid); ?> line in nextgen-gallery/view/gallery.php file.
While searching the forum there i found a post with a similar problem a while ago, but his problem was not resolved. I therefore decided to post this solution and hope it comes in handy to someone :).