Error Showing in Header of Marketpress site

Hi all,

I am receiving this message on one of my sites in my network;

Warning: in_array() expects parameter 2 to be array, null given in /home/****/public_html/wp-includes/post-template.php on line 1039

I have recently updated to wp3.5 and it only appears when clicking on a product catergory. Three lines of the above error, one for each the menu items??? not sure only guesing.

Anyone any clues how to approach this one? Marketpress or Theme?

site: Shabby Shac

theme: zenon-lite

Thank you in advance,