Sometimes when updating or upgrading different packages on your Ubuntu specially kernel updates, Zend Server tends to break up and the whole packages system too, you usually get errors like "bad inconsistency" of package php-zend-server-ce-php-5.x and you are asked by the system to reinstall this package but that's also impossible due to the changes the update has performed.
In order to fix this issue try following the next steps:
sudo /usr/local/zend/bin/zendctl.sh stop => stop zend server service
sudo rm -rfv /usr/local/zend/tmp/* => remove zend server's cache and/or temp files
sudo /usr/local/zend/bin/zendctl.sh start => start the service again
and reinstall the zend-server-ce-php-5.x package using synaptic, or dpkg.
Hope this helps!