After upgrading from 1.8.12 to 1.8.13 the Web front end no longer works. The system continues to do monitoring as email notifications are still being received. It just seems to be frontend problem.
The initial configuration of the fornt end works succesfully up until step 8 "Finish"> When the Finish button is clicked on the browser posts the page, but the web server never comes back. Eventually the following error is logged in /var/logs/http/error.log
[Tue May 15 21:38:44 2012] [error] [client 192.168.42.91] PHP Fatal error: Allowed memory size of 775946240 bytes exhausted (tried to allocate 523800 bytes) in /var/www/html/zabbix-1.8.13/include/copt.lib.php on line 524, referer: http://zabbix02/zabbix/setup.php
In php.ini memory_limit = 740M, but it does not seem to matter what memory_limit is set to. It was originally set to 256M and every time I increased it the the installation of the frontend fails at that memory size.
The Postgresql postmaster process uses a lot of CPU from the time the Finish button is clicked on until the failure is logged.