I been encountering this problem a days ago. After the service comes ok, it is OK in status web interface but the host is DOWN in web interface. Also did not received any email pertaining to the recovery of that service. I go to /var/mail/nagios and it’s pending 4 hours already. I restart sendmail but still no action. I rm nagios and touch a new one.
Can anyone help me with this? 
Does the /var/mail/nagios file have the correct permissions?
ls -la /var/mail/nagios
-rw-rw---- 1 nagios mail 0 Jun 5 13:17 /var/mail/nagios
For the host that is down in web interface, disable and then enable checks of this host by using the web interface. After that, force an immediate check of all services on that host by using the web interface.
the permission is right. I restart NAGIOS and it is now ok. I don’t want to do this again probably visit again this thread just incase it happen again.
still encounter the same problem!!!
OK, we haven’t looked at all of your .cfg files. I suggest, that you start from page 1 in the docs, and do it all over again. I’ve done my setup many times when I first started and it doesn’t hurt to read the docs several times over. You haven’t enabled active checks, or something in one of your .cfg files. Perhaps you have nagios running in 2 instances. Reboot perhaps, but we don’t have enough details to fix this.
If this is not V1.2 then I"m sorry, I’m not about to debug the beta’s of version 2.x since I spent alot of time installing it once, and it’s still buggy. V1.2 does everything you need it to do so install v1.2 from scratch.
PS; meulie.net/forum_viewtopic.php?21.3837
Permissions on files have caused about 50 problems in this forum alone. So check all your folders, all your files, for permissions problems.
In particular, check your objects.cache file, since it looks like you are using the beta version of nagios v2.0. And if you are, I have to ask why? Unless you are a nagios expert, why would you want to start your nagios experience by troubleshooting all the bugs in the beta? My suggestion is start with something NOT buggy, v1.2 and if you get bored and want to troubleshoot a beta, then go for it later, but not now.