> In the access log for x-payments each entry says Customer Information Manager is
> not enabled.
So you use Auth.net CIM, right?
Such errors mean something is not enabled or configured from Auth.net's side. Please make sure you finalize everything and have activated CIM account at Auth.net.
Also, make sure you copied all Auth.net CIM params needed for integrated software to operate into your X-Payments account.
http://help.x-cart.com/index.php?title=X-Payments:User_manual#Viewing_a_Payment_Configurati on.27s_details