well, i could not do memtest86+ on that machine. So i took the HDD and USB wifi tl-wn7200d. to another machine, and it is still crashing.
by the way
i did test that before on pfsense 2.x and it was crashing too. and i thought it might work on m0n0wall 1.8.x
this is my config.xml file
<?xml version="1.0"?>
<m0n0wall>
<version>2.0</version>
<lastchange>1391846311</lastchange>
<system>
<hostname>m0n0wall</hostname>
<domain>local</domain>
<dnsserver/>
<dnsallowoverride/>
<username>admin</username>
<password>$1$2xGLA75j$W/jiJc00HYBZX7kFjxjQv0</password>
<timezone>Etc/UTC</timezone>
<time-update-interval>300</time-update-interval>
<timeservers>2.m0n0wall.pool.ntp.org</timeservers>
<webgui>
<protocol>http</protocol>
<mbmon>
<type>C</type>
</mbmon>
<certificate/>
<private-key/>
</webgui>
<harddiskstandby/>
</system>
<interfaces>
<lan>
<if>re0</if>
<ipaddr>10.10.101.55</ipaddr>
<subnet>16</subnet>
<media/>
<mediaopt/>
</lan>
<wan>
<if>rl0</if>
<ipaddr>dhcp</ipaddr>
<subnet/>
<gateway/>
<blockpriv/>
<dhcphostname/>
<media/>
<mediaopt/>
</wan>
<opt1>
<descr>WLAN</descr>
<if>wlan0</if>
<ipaddr/>
<subnet>31</subnet>
<bridge>lan</bridge>
<enable/>
</opt1>
</interfaces>
<staticroutes>
<route>
<interface>lan</interface>
<network>0.0.0.0/32</network>
<gateway>10.10.10.1</gateway>
<descr/>
</route>
</staticroutes>
<pppoe>
<username/>
<password/>
<provider/>
</pppoe>
<pptp>
<username/>
<password/>
<local/>
<subnet/>
<remote/>
</pptp>
<dyndns>
<type>dyndns</type>
<username/>
<password/>
<host/>
<mx/>
<server/>
<port/>
</dyndns>
<dnsupdate/>
<dhcpd>
<lan>
<range>
<from>192.168.1.100</from>
<to>192.168.1.199</to>
</range>
<defaultleasetime/>
<maxleasetime/>
<next-server/>
<filename/>
</lan>
</dhcpd>
<pptpd>
<mode/>
<nunits>16</nunits>
<redir/>
<localip/>
<remoteip/>
</pptpd>
<dnsmasq>
<enable/>
</dnsmasq>
<snmpd>
<syslocation/>
<syscontact/>
<rocommunity>public</rocommunity>
</snmpd>
<diag/>
<bridge>
<nospoofcheck/>
</bridge>
<syslog>
<reverse/>
<nentries>50</nentries>
<remoteserver/>
<remoteport/>
</syslog>
<nat>
<portrange-low/>
<portrange-high/>
</nat>
<filter>
<rule>
<type>pass</type>
<interface>wan</interface>
<source>
<any/>
</source>
<destination>
<any/>
</destination>
<descr/>
</rule>
<rule>
<type>pass</type>
<interface>opt1</interface>
<source>
<any/>
</source>
<destination>
<any/>
</destination>
<descr/>
</rule>
<rule>
<type>pass</type>
<interface>lan</interface>
<source>
<any/>
</source>
<destination>
<any/>
</destination>
<descr>Default LAN -> any</descr>
</rule>
<rule>
<type>pass</type>
<descr>Default IPsec VPN</descr>
<interface>ipsec</interface>
<source>
<any/>
</source>
<destination>
<any/>
</destination>
</rule>
<bypassstaticroutes/>
<tcpidletimeout/>
</filter>
<shaper/>
<ipsec>
<dns-interval/>
</ipsec>
<aliases/>
<proxyarp/>
<wol/>
<croen>
<interval>10</interval>
</croen>
<wlans>
<wlan>
<if>run0</if>
<descr/>
<standard>11g</standard>
<mode>hostap</mode>
<ssid>m0n0</ssid>
<channel>8</channel>
<txpower>23</txpower>
<wep/>
<wpa>
<mode>none</mode>
<version/>
<cipher/>
<psk/>
<radius>
<server/>
<authport/>
<acctport/>
<secret/>
</radius>
</wpa>
</wlan>
</wlans>
<dhcrelay>
<server>10.10.10.1</server>
<lan>
<enable/>
</lan>
</dhcrelay>
</m0n0wall>