No catsgory listings after upgrade

Hi there,

I just upgraded to the latest and now if I click on a category, it does not list the ebook titles in the category.
Please see store.theebooksale.com.

Other points to note:

• the mobile version of the store m.theebooksale.com seems to default to the main store also (I use the multi-site module)
• if I click on a category that has just 1 product, it displays ok (I guess, this is because it defaults to the actual product page instead of the category listing page).
• The "Congratulations! You have successfully installed your Zen Cart™ E-Commerce Solution" message shows up on the storefront...so it seems to think it's a new install.
• Also, the 'Add to cart' buttons are not the graphics that are associated with this template.

Anyone have any ideas?
Many thanks,
Richie.