"IE cannot display the /shopping-cart/shipping/" page

We're setting up MarketPress and testing a single product. When we press "checkout now" we always get this error message: "IE cannot display the /shopping-cart/shipping/ page"

We sell only downloadable products, so no shipping is ever charged.

Store settings

Current shipping settings:
General: apply tax to shipping = no

Presentation: Store URL slugs: we noted that store/shipping/ is not shown.

Shipping: Choose Target Countries: we have tried both scenarios: selecting all countries and selecting none countries. Did not resolve error message.

Shipping: No Shipping is selected

Test Product Setting
On our Test Product post, we've entered a download URL.