[Flow] I get an access error when logged in but not when logged out

[Calgacus map Brude]

I get an access error (403) when I hit a certain  page ( mysite.com/shop/meta-pages/shopping-cart/checkout/order-placed.html after coming back from a payment gateway ) when I am logged in to my site, but when I am not logged in I get no such error.  Where/how is the access specified?

Thanks 

I originally asked this question with a  few more details (log and exception messages) on stack at: 
http://stackoverflow.com/questions/27049610/typo3-flow-access-denied-when-logged-in-but-not-when-not-logged-in-why