Zen Cart 1.5.4 upgraded from 1.5.3 in February 2015 via official upgrade procedure with FTP and zc_install.
PHP 5.4.28, MySQL 5.5.42-cll

First time install of latest versions of Admin New Customer, Edit Orders, Admin New Orders in exactly that order. These are the only plug-ins installed.

FYI When I installed Admin New Customer the admin_new_customer_3\1_affected_files_151\includes\functions\password_funcs.php broke the admin login page in that it wouldn't accept any passwords so I had to revert to "clean" 1.5.4 version. --> I'm still testing the functionality of the plug-in, but will an update soon be available?