Plugin/Widget conflict?

When I go to any page in my site, the Recent Posts widget in my left sidebar displays as it should. But when I click on a category in my WP-Ecommerce shopping cart, the Post titles ALL change to the name of that category. It’s just the weirdest thing.

It seems fairly obvious that there’s a conflict between the built-in widget and the shopping cart plugin, but I don’t know where to start looking. Can anybody help? Would a link help? Here: http://propsmaster.co.uk/ (then select “Catalogue” and then any category to see what happens).