Erro Zend_Session::start

Galera estou com esse erro do zend já tentei fazer varias coisas mais nada funcionou entao espero que vocês possam me ajudar

Desde já agradeço

Fatal error: Uncaught exception 'Zend_Session_Exception' with message 'Zend_Session::start() - /home/mcinfor-saude/webapps/ROOT/sitemc/Zend/Session.php(Line:480): Error #8 session_start() [<a href='function.session-start'>function.session-start</a>]: ps_files_cleanup_dir: opendir(/tmp) failed: Permission denied (13) Array' in /home/mcinfor-saude/webapps/ROOT/sitemc/Zend/Session.php:493
Stack trace:
#0 /home/mcinfor-saude/webapps/ROOT/sitemc/index.php(61): Zend_Session::start()
#1 {main}
thrown in /home/mcinfor-saude/webapps/ROOT/sitemc/Zend/Session.php on line 493