Register and Continue button for new user

[Guest Lynchy]

When a new user comes through my store and adds items to their cart then tries to checkout they are sent to the page with a Register and Continue button... When they click this they are asked for reg info which goes fine then when finished they are sent back to the cart and then sent to the payment gateway all goes well but when the confirmation message is dispalyed they see "You must login to see this page" and the order status is stuck in pending... If I go thru reg process then logout/login everything is fine and returning customers is fine. It seems like a session id needs to get passed but not sure how... ANy thoughts??