Any idea what would be causing these errors?

I installed Classifieds, when there are no classifieds added, the page throws a bunch of errors. Some assistance in narrowing down where the problem could be would be greatly appreciated.

Wordpress has been upgraded to the newest version.

The WP files in question have not been changed, so they are the files that come with the newest install.

Errors as follows:

Notice: Undefined offset: 0 in /chroot/home/waymarcc/waymarc.com/html/wp-includes/query.php on line 2848 Notice: Trying to get property of non-object in /chroot/home/waymarcc/waymarc.com/html/wp-includes/query.php on line 3645 Notice: Trying to get property of non-object in /chroot/home/waymarcc/waymarc.com/html/wp-includes/query.php on line 3647 Notice: Trying to get property of non-object in /chroot/home/waymarcc/waymarc.com/html/wp-includes/query.php on line 3649 Notice: Trying to get property of non-object in /chroot/home/waymarcc/waymarc.com/html/wp-includes/query.php on line 3650 Notice: Trying to get property of non-object in /chroot/home/waymarcc/waymarc.com/html/wp-includes/query.php on line 3658 Notice: Trying to get property of non-object in /chroot/home/waymarcc/waymarc.com/html/wp-includes/query.php on line 3673 Notice: Trying to get property of non-object in /chroot/home/waymarcc/waymarc.com/html/wp-includes/post-template.php on line 29

Thoughts?