Hello Guy, thank you for taking the time to file this bug report and help us make Ubuntu better.
Can you enable core dumps for apache so we get a core file when it segfaults?
This *should* do the trick:
service apache2 stop
ulimit -c unlimited
service apache2 start
After it has crashed, you can backtrace it yourself:
gdb /usr/sbin/apache2 /path/to/core/file (probably /tmp/something, look in /var/log/error.log)
and paste the output here.
Marking Incomplete pending response from Guy.