I have an odd problem with wp_nav_menu effecting the post order on subsequent post queries made throughout the site I'm working on. I'm using a very heavily modified commercial theme and wp_nav_menu is included within the first few lines of header.php as normal. This is the particular code (which seems normal to me):
wp_nav_menu( array( 'container' => '', 'menu_class' => 'nav1', 'theme_location' => 'primary' ) );
The problem is that ANY post query that is made after the header has been included returns posts ordered by menu_order no matter what orderby argument has been set for both query_posts() and individual WP_Query instances.
I've narrowed it down to the nav menu because if I simply remove the wp_nav_menu function from header.php, all subsequent post queries order by date descending as expected. Any attempt to manually set orderby=date&order=DESC is completely ignored if I have the wp_nav_menu in the header.
This has got me stumped. Anybody experienced anything like this and know what might be causing it?