PHP Fatal error:  Allowed memory size of 262144 bytes exhausted (tried to allocate 79 bytes) in Unknown on line 0

vi /etc/php5/apache2/conf.d/ZendOptimizer.ini

zend_extension=/usr/local/lib/ioncube/ioncube_loader_lin_5.3.so 
zend_extension=/usr/lib/php5/20090626/ZendGuardLoader.so 
zend_optimizer.optimization_level = 15 
zend_loader.enable=1 
zend_loader.disable_licensing=1