Disabled SSL by changing all the https to http in both configure.php files. Changed all the SSL=true to false in both configure.php

Same result. Auth.net SIM approving the transaction but nothing happening within ZC. So the SSL in the live site vs no SSL in the test site doesn't appear to be the cause.

Server log for the only auth.net SIM response, but nothing happens within ZC

198.241.168.60 - - [13/Nov/2014:11:00:43 -0800] "POST /index.php?main_page=checkout_process&action=confirm HTTP/1.1" 302 208 "-" "-"
Looking @ server info differences between the two servers shows a few differences. The most significant (to me) is the test site has an entire section labeled SUHOSIN where the live server has nothing.