Hi
I have the same problem and it has nothing to do with the theme. The error logs clearly indicate that there something wrong with the functions_general.php of the module. I have tried it on a clean installation and it keeps breaking. I can replace the functions_general.php file with the zen 1.51 original and the web site comes back again.
20-Feb-2014 11:14:26 UTC] PHP Fatal error: Cannot redeclare zen_create_random_value() (previously declared in xxxxxxxxxx\includes\functions\functions_general.php:626) in xxxxxxxxxx\includes\functions\password_funcs.php on line 86

The same error has been acknowledged as a conflict between an old version and a new version of the file by DrByte. http://www.zen-cart.com/showthread.p...om_value%28%29

If someone could check that out will be greatly appreciated.
Thanks
Tassos