Ok I think I may have worked this out from two other posts, if turning the sessions off doesn't work try adding these lines to these files
includes/modules/pages/product_info/header_php.php
change
$zco_notifier->notify('NOTIFY_HEADER_START_PRODUCT_INFO');
require(DIR_WS_MODULES . zen_get_module_directory('require_languages.php'));
to
$zco_notifier->notify('NOTIFY_HEADER_START_PRODUCT_INFO');
$_SESSION['navigation']->set_snapshot();
require(DIR_WS_MODULES . zen_get_module_directory('require_languages.php'));
and then
includes>init_includes>init_customer_auth.php
add this line at the bottom
if ($request_type == 'NONSSL') $_SESSION['navigation']->set_snapshot();
I'm on fasthosts windows box and this just saved my bacon, hope it helps you
Gary



