FreeBSD 7 server in hang with nagios

[Gian Paolo Buono]

Hi, I have on my server ibm 3650 FreeBSD 7.1-RELEASE-p2 and the proccess
that running are nagios-3.0.3, apache-2.2.8 and heartbeat-1.2.5_3;
random after some day machine becomes semi-dead, the ping respond but
any stack (ssh,http) don't work and heartbeat don't switch the
resources I can't loggon and I must reboot. In the syslog there
isn't any message for trobleshotting the problem. Any idea ? Sorry
for my english
Best Regards