Nagios shutting down

After i setted up parent-child relationship between some hosts, sometimes nagios shutting down no reason.
When i start it again, it starts normally, but stopping after 1minute. And if i disable all child hosts, it stays to work. After that i can enable the child hosts too and nagios works again perfectly.
It will happen not very often, but maybe once or twice a week.

Regards,

Mosse

Are you sure it is due to parent/child relationships?

What does nagios.log say when Nagios stops working?
What does syslog say about it?

Log says nothing.
For now it works well and right now no problems with that. But it was really strange for me.
Nov 27 09:26:29 info nagios: Finished daemonizing… (New PID=15469)
Nov 27 09:26:34 info nagios: Successfully shutdown… (PID=15469)

Still same problem.
Have parents-childs. If whole segment is going down, nagios send about parent notification, as it have to do. But after that nagios shutting down. Logs shows just :
1235826931] Caught SIGSEGV, shutting down…
[1235982773] Nagios 3.0a4 starting… (PID=1022)

Edit. Nagios shutting down, when segment is online again and it should send the notification out.