Need Help Deciphering members_directory_output Error

Our error log is filling up with numerous instances of the following...

[19-Nov-2013 18:30:00 UTC] WordPress database error You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '-10, 10' at line 1 for query SELECT * FROM wp_site_posts WHERE post_author = 2681 ORDER BY site_post_id DESC LIMIT -10, 10 made by require('wp-blog-header.php'), require_once('wp-includes/template-loader.php'), include('/themes/wpmu-nelo-child/page.php'), the_content, apply_filters('the_content'), call_user_func_array, members_directory_output

On average, I see a couple of these every minute. The only thing that changes is the post_author ID.

I can't tell if this is being thrown by the Members Directory plugin, Post Indexer, or the Nelo theme.

Any feedback is greatly appreciated. Thanks!

FYI: We're on our own Linux box running MySQL version 5.5.32-cll and PHP version 5.3.26.