It's possibly something to do with wrong xml formatting, a missing bracket or something. Have you tried reverting back to the previous xml file and seeing if it crashes still? If not, that's what you should do
<?xml version="1.0" encoding="UTF-8"?>
<monster name="The Butcher" tp="1" species="human" nameDescription="a The Butcher" race="blood" experience="19000" speed="200" manacost="0">
<health now="20000" max="20000"/>
<look type="278" head="114" body="132" legs="114" feet="114" addons="3" corpse="3128"/>
<targetchange interval="60000" chance="0"/>
<strategy attack="100" defense="0"/>
<flags>
<flag summonable="0"/>
<flag attackable="1"/>
<flag hostile="1"/>
<flag illusionable="0"/>
<flag convinceable="0"/>
<flag pushable="0"/>
<flag canpushitems="0"/>
<flag staticattack="30"/>
<flag lightlevel="0"/>
<flag lightcolor="0"/>
<flag targetdistance="3"/>
<flag runonhealth="0"/>
</flags>
<attacks>
<attack name="fury_sound" interval="9500" min="-900" max="-1100"/>
<attack name="Fire Wall" interval="2500" min="-500" max="-650"/>
</attacks>
<defenses armor="40" defense="45">
<defense name="Ultimate Healing" interval="2000" chance="5" min="40" max="50"/>
</defenses>
<immunities>
<immunity physical="0"/>
<immunity energy="0"/>
<immunity fire="0"/>
<immunity poison="0"/>
<immunity lifedrain="0"/>
<immunity paralyze="1"/>
<immunity outfit="0"/>
<immunity drunk="0"/>
<immunity invisible="1"/>
</immunities>
<voices interval="2200" chance="5">
<voice sentence="I neeed some flesh from ur arms."/>
<voice sentence="Please come closer."/>
</voices>
<loot>
<item id="2160" countmax="100" chance1="10000" chancemax="0"/>
<item id="2160" countmax="100" chance1="10000" chancemax="0"/>
<item id="2671" countmax="4" chance1="4000" chancemax="0"/>
<item id="2671" countmax="6" chance1="10000" chancemax="0"/>
<item id="2671" chance="2000"/>
<item id="2160" chance="100000">
<inside>
<item id="2148" countmax="50" chance1="80000" chancemax="0"/>
<item id="2148" countmax="50" chance1="80000" chancemax="0"/>
<item id="2387" chance="4000"/>
<item id="2792" countmax="5" chance1="6666" chancemax="0"/>
<item id="2793" countmax="2" chance1="6666" chancemax="0"/>
</inside>
</item>
</loot>
</monster>
This text is among the monsters that disappear, is there any error I am using Otx now