Nagios error 500

hello there.
i just install Nagios3 on server where im using ISPConfig3. I can enter core statistic site for nagios on www.example.com/nagios3/ but when i try to reach some of the services or any other type of monitoring i got ERROR 500. how can i fix it ?

 

Hi try to uncheck suEXEC in web site options.

 

thanks. i read about it and i fix it.
if someone wants to use nagios on ubuntu 12.04 server this is the how to that i use
https://library.linode.com/server-monitoring/nagios/ubuntu-12.04-precise-pangolin