[Plugin: WooCommerce] Display problems

On the main shop page, I have displayed 4 categories with an image included. Now everytime I go there again for the first time, the categories are displayed vertically. Once I refresh the page, they are shown as they should be shown (4 next to eachother) I think this also happens with the products within a categorie.

And then there’s the problem with the sidebar / widgets. They are being shown twice. Once in the right place, the right sidebar, and once in the body of the page. The latter disappears when you hit refresh.

So anyone has an idea what’s going on?