ok, i found the cause of the problem. i take it all back ubuntu, apologies :)
i was still using an old version of a php.ini file in a non-ubuntu-standard location: /etc/php.ini as opposed to /etc/php5/apache2/php.ini
when i reinstalled everything and put in a recommended php.ini (from /user/share/docs/php5-common/examples) and then reinstalled the zend-optimizer. now everything back to normal and completely from standard packages.