I seem to be experiencing a similar problem to the one described here; however, in my case, normal customer logins in Chrome do not work, but admin logins do. I have added the debugging code that DXBLouie used, in my /includes/modules/pages/login/header_php.php file: sure enough, the tokens never match and I get the message "There was a security error when trying to login." I can only experience this in Chrome. Firefox, Opera, Safari, and IE all seem to work fine.
I am running Zen Cart 1.3.9h on PHP 5.2.8. I upgraded from 1.3.9e today. This did not solve the problem.
Customers are reporting trouble with Chrome logins and it's understandably annoying them, so I need to solve this soon. Any help welcomed.
I am running Zen Cart in a subdirectory: could this have anything to do with it?