Paypal redirects back to login or clears the cart contents

[Propaganda]

When I use Paypal Payments Pro or Express when I click continue or confirm (depending on the payment type selected) the site either logouts the user then goes to the login screen or back to the cart with the contents cleared.

 

When I use Paypal standard everything goes through just fine to the sandbox server.

 

 

I restored an old backup of oscom which was a near virgin install and it did the same thing. Oh, version 1.0 on both modules. I am waiting for the step by step install instructions to come out for the newer one.

 

Any insights to this?

 

Thanks.