WP + MarketPress + Authorize.NET = Busted Orders page

I have set up MarketPress eCommerce on this WordPress site (www.mwauniversity.org). Tested an order and it went through fine. But when I click on the "Manage Orders" page in the dashboard, it gags. All the other plug-in pages work fine (Store settings, Products, etc.), but the Manage Orders page gags. See attached screeners.