Fatal Error Message

I’m updating the look of my website using twentyten weaver theme 3.0.4

I installed a plugin called ‘Pages Posts’ which should allow me to display certain posts I want on certain pages I choose, but when I went to view the page I wanted posts to show up on, I got this message: “Fatal error: Call to a member function have_posts() on a non-object in /home3/bumpkina/public_html/wp-includes/query.php on line 641”

I contacted my web host’s support and they said the problem is with the actual plugin – I know there’s a way to correct this in the plugin’s php file on wordpress, but I have no idea how to write script or what to look for to fix this problem. I need some serious hand-holding. Can anyone please, please help me?