Some FYI that everyone can use.
PHP Session.use_trans_sid should be disabled, period.
Register Globals should be OFF because Zen Cart doesn't need it and OFF gives your site better security.
If PHP is run as Apache Module
## public_html/.htaccess
php_flag session.use_trans_sid off
php_value register_globals off
If PHP is run as CGI
## public_html/php.ini
session.use_trans_sid = off
register_globals = off
---
DusX, have you spoken with your Hoster about this problem and/or their setup for using PHP sessions?



