Live hosts some time shows up and some time shows down

Dear friends
I am using nagios 3.2.0 in fedora 8, with this more then 100 of nodes monitoring with this. now a days i am facing some strange problem. The host which ping properly from nagios server still it shows some time down and when i am refreshing the browser it shows up. means on line monitoring is confusing whether node gets down or up. kindly plz suggest.
with regs
rajnish

check that you don’t have two nagios instances running…
stop the nagios service, check with ps there are no other nagios instances, if there is still something running use the kill command and start again. This was a problem time ago when using the nagios restart command… i don’t know if it still existst in the latest releases.

Luca