PayPal Website Payments Pro: This transaction cannot be processed. The merchant's account is not able to process transactions
The ability to do a Direct Payment transaction is what you get with PayPal Pro, as I understand it (i.e. allows you to host the payment page on CiviCRM). 

But you do likely want to update to the latest 4.7.x, I have heard of issues with PayPal, though not this drastic.