Host State Changing

NAGIOS: 3.0.6
HOST: Linux box

I have just one host in particular that changes states frequently. The host goes from “ok” to “warning” to being red and being down. Then it quickly (a matter of seconds) goes back to the normal condition. Here’s is the command it is using:

/usr/local/nagios/libexec/check_ping -H 67.63.34.47 -w 3000.0,80% -c 5000.0,100% -p 1

Here are the messages I receive:

06-19-2009 08:51:29] SERVICE ALERT: A2BILLING;Host Monitor;CRITICAL;SOFT;1;SIP CRITICAL - Test Duration: 2928.103 ms
06-19-2009 08:22:23] SERVICE ALERT: A2BILLING;Host Monitor;WARNING;HARD;2;SIP WARNING - Test Duration: 726.147 ms

Does anyone have any ideas why this is happening? I ran “vmstat”, “top”, and “sar” on that particular host. There’s nothing out of the ordinary in there.