Nagios service can not start

Since a restart, We can not start our check_mk monitoring site. I don’t realy know where to search the exact problem, but i’ll paste the start processing message. If you need any other information please tell me. I am not realy into this forum posting thing.

root@omd_hvsz:/opt/omd/sites/check_mk/etc/pnp4nagios# omd disable check_mk
Unmounting temporary filesystem…OK
Disabling Apache configuration for this site…OK
Restarting Apache…OK
root@omd_hvsz:/opt/omd/sites/check_mk/etc/pnp4nagios# omd reload
root@omd_hvsz:/opt/omd/sites/check_mk/etc/pnp4nagios# omd enable check_mk
Re-enabling Apache configuration for this site…OK
Restarting Apache…OK
root@omd_hvsz:/opt/omd/sites/check_mk/etc/pnp4nagios# omd start check_mk
Creating temporary filesystem /omd/sites/check_mk/tmp…OK
Starting mkeventd (builtin: syslog-udp)…OK
Starting rrdcached…OK
Starting npcd…OK
Starting nagios…
Nagios Core 3.5.1
Copyright © 2009-2011 Nagios Core Development Team and Community Contributors
Copyright © 1999-2009 Ethan Galstad
Last Modified: 08-30-2013
License: GPL

Website: http://www.nagios.org
Reading configuration data…
Read main config file okay…
Processing object config directory ‘/omd/sites/check_mk/etc/nagios/conf.d’…
Processing object config file ‘/omd/sites/check_mk/etc/nagios/conf.d/check_mk_objects.cfg’…
Processing object config file ‘/omd/sites/check_mk/etc/nagios/conf.d/pnp4nagios.cfg’…
Processing object config file ‘/omd/sites/check_mk/etc/nagios/conf.d/templates.cfg’…
Processing object config file ‘/omd/sites/check_mk/etc/nagios/conf.d/check_mk_templates.cfg’…
Processing object config file ‘/omd/sites/check_mk/etc/nagios/conf.d/jmx4perl_nagios.cfg’…
Read object config files okay…

Running pre-flight check on configuration data…

Checking services…
Checked 2651 services.
Checking hosts…
Checked 398 hosts.
Checking host groups…
Checked 21 host groups.
Checking service groups…
Checked 3 service groups.
Checking contacts…
Checked 13 contacts.
Checking contact groups…
Checked 3 contact groups.
Checking service escalations…
Checked 0 service escalations.
Checking service dependencies…
Checked 11 service dependencies.
Checking host escalations…
Checked 0 host escalations.
Checking host dependencies…
Checked 0 host dependencies.
Checking commands…
Checked 52 commands.
Checking time periods…
Checked 3 time periods.
Checking for circular paths between hosts…
Error: The host ‘…’ is part of a circular parent/child chain!
Error: The host ‘…’ is part of a circular parent/child chain!
Error: The host ‘…’ is part of a circular parent/child chain!
Error: The host ‘…’ is part of a circular parent/child chain!
Error: The host ‘…’ is part of a circular parent/child chain!
Error: The host ‘…’ is part of a circular parent/child chain!
Error: The host ‘…’ is part of a circular parent/child chain!
Error: The host ‘…’ is part of a circular parent/child chain!
Checking for circular host and service dependencies…
Checking global event handlers…
Checking obsessive compulsive processor commands…
Checking misc settings…

Total Warnings: 0
Total Errors: 1

***> One or more problems was encountered while running the pre-flight check…

 Check your configuration file(s) to ensure that they contain valid
 directives and data defintions.  If you are upgrading from a previous
 version of Nagios, you should be aware that some variables/definitions
 may have been removed or modified in this version.  Make sure to read
 the HTML documentation regarding the config files, as well as the
 'Whats New' section to find out what has changed.

Starting apache…OK
Initializing Crontab…OK

I have no idea what happend but I 1 month ago i made a backup, i copied everything from the zipped file and now its working…

smh

Nagios complains about a circular parent relationship. Have a look at the WATO configuration of your hosts and check the parent definitions.