FreeBSD constantly hanging

[Deceased]

Hi,

I have a serious problem, that I cannot solve my self :(

I have freebsd 6.2 router that has 3 NICs (lan, wan, dmz), suddenly 
(about two weeks ago) it started to hang without leaving anything in 
logs. I thought that it was hardware problem. So at first I changed 
motherboard, ram, cpu, NIC's, PSU, I kept changing everything but it was 
still hanging :/, reinstalled, but it didn't help.

Then we got brand new PC and I did fresh install of 6.2_RELEAS-200708, 
but to my surprise it was still hanging. There may by power issues, but 
in the same place there are 2 more servers : HP Proliant ML310 G4 with 
windoze and second is simple P4 1.6Ghz with 6.0-STABLE, both of them are 
not hanging.

Hanging machine is connected to the APC 350 ups, but it does not help.

Thank You for your thoughts.

====

below there is a list of ports installed and changed make.conf params:

arc-5.21o_1         Create & extract files from DOS .ARC files
arj-3.10.22         Open-source ARJ
autoconf-2.59_3     Automatically configure source code on many Un*x 
platforms
autoconf-wrapper-20070404 Wrapper script for GNU autoconf
bind94-base-9.4.1.1 The BIND DNS suite with updated DNSSEC and threads
clamav-0.91.2       Command line virus scanner written entirely in C
cvsup-without-gui-16.1h_3 General network file distribution system 
optimized for CVS
dansguardian-2.9.8.2 A fast, feature-rich web content filter for Squid 
proxy ser
ezjail-2.1          A framework to easily create, manipulate and run 
FreeBSD ja
gettext-0.16.1_3    GNU gettext package
gmake-3.81_2        GNU version of 'make' utility
help2man-1.36.4_1   Automatically generating simple manual pages from 
program o
isc-dhcp3-server-3.0.5_2 The ISC Dynamic Host Configuration Protocol server
lha-1.14i_6         Archive files using LZSS and Huffman compression 
(.lzh file
libevent-1.3b       Provides an API to execute callback functions on 
certain ev
libgmp-4.2.1_2      A free library for arbitrary precision arithmetic
libiconv-1.9.2_2    A character set conversion library
libnet10-1.0.2a_2,1 A C library for creating IP packets
libtool-1.5.22_4    Generic shared library support script
m4-1.4.9            GNU m4
mysql-client-5.0.45 Multithreaded SQL database (client)
openssh-portable-overwrite-base-4.7.p1,1 The portable version of 
OpenBSD's OpenSSH
p5-gettext-1.05_1   Message handling functions
pcre-7.3            Perl Compatible Regular Expressions library
perl-5.8.8          Practical Extraction and Report Language
pftpx-0.8_3         Much enhanced ftp proxy for pf that supports most 
ftp proto
snort-2.7.0.1       Lightweight network intrusion detection system
squid-2.5.14_4      HTTP Caching Proxy

== make.conf
CPUTYPE?=pentium4
CFLAGS= -O2 -pipe
CXXFLAGS+= -fconserve-space
COPTFLAGS= -O -pipe

Klernel is GENERIC