ijk;
I saw the other thread you started,
http://daemonforums.org/showthread.php?t=1305. It's time to upgrade. If what you have listed as your server config (Freebsd 5.4-RELEASE apache2.0.63 php5.2.6 zend optimzer v3.3.0 mysql5.0.51 postfix2.5.1) is all that is on the "box" you have a few choices.
Upgrade route:
#1 -
http://www.daemonology.net/freebsd-upgrade-5.4-to-6.0/
#2 - Backup what you need from that server to another machine and start over with 7.0.
Re; Apache error
Something tells me that not all the sites listed in the "VHost" config are producing the error. It's only one or, maybe two right? And, the site and or sites producing the errors are using a CMS, maybe a Forum or, a script. If It's a script disable it and see what happens. If it's one of the other two they aren't setup correctly or, they aren't compatable with the server enviroment.