Odd error

I keep getting:

[05-Mar-2013 21:23:49 UTC] PHP Fatal error: Call to a member function have_posts() on a non-object in /webstuff/canalblogs/wp-content/plugins/post-indexer/classes/networkquery.php on line 737

which is breaking the global post feed.

The line in question is:

return $network_query->have_posts();