Not all that basic, since I don't know exactly what it means, but I would check includes/modules/sideboxes/andover_modern to see if the languages_header.php file exists and isn't corrupted. I would probably re-upload that file directly from the template files to that folder. The languages section in the header (which doesen't exist in the Classic template) is where your page is dying.

There's also a support thread for that template here:

http://www.zen-cart.com/showthread.p...hlight=andover