I had the following problem: Every Sunday my apache instance crashed. All my /var/log/apache2/error showed was:
[Sun Sep 21 00:23:03 2014] [notice] seg fault or similar nasty error detected in the parent process
I have no weekly cronjob running so it had to be something else... My webserver is running a Debian 7.6 install. Beside Wordpress and some other webprojects I use Kolab for my emails. You could easily reproduce the crash by running an apache reload, not restart!
As mentioned in the comments there is a better solution of Christian in https://issues.kolab.org/show_bug.cgi?id=2050#c68:
on Debian (Wheezy and Jessie) adding the following entry to /etc/apache2/envvars prevents apache to crash:export ZEND_DONT_UNLOAD_MODULES=1
After some research I tumbled over a hint about a Kolab ini-file which causes the problem. All I had to do was to change lines in /etc/php5/mods-available/kolab.ini
extension=kolabshared.so extension=kolabobject.so extension=kolabcalendaring.so
;extension=kolabshared.so extension=kolabobject.so ;extension=kolabcalendaring.so
I guess it is highly advisable to run Kolab on a fedora/centos/redhat system, because thats the OS system development of Kolab is run on. The Debian port seams a little bit buggy and not well supported.