Hi Philip,
here is my cart config screenshot:
Even if I use the option "URL where you will be redirected when the cart is empty" to redirect to my thank you page, there is still the problem with logging off after confirming the order:
1) On my thank you page there is a form for new customers to fill in. And some values to that form are passed from their registration data. So if they are logged off they have to fill in this values themselves.
2) Customers can't use their accounts directly after ordering.
Thank you for your time.
Denis