2013-09-04 18:24:41 [SEVERE] Could not pass event CreatureSpawnEvent to Rebalance Villagers v1.5.2
org.bukkit.event.EventException
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:427)
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
	at org.bukkit.plugin.TimedRegisteredListener.callEvent(TimedRegisteredListener.java:47)
	at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:478)
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:463)
	at org.bukkit.craftbukkit.v1_6_R2.event.CraftEventFactory.callCreatureSpawnEvent(CraftEventFactory.java:256)
	at net.minecraft.server.v1_6_R2.World.addEntity(World.java:974)
	at net.minecraft.server.v1_6_R2.World.addEntity(World.java:945)
	at net.minecraft.server.v1_6_R2.EntityZombie.bW(EntityZombie.java:398)
	at net.minecraft.server.v1_6_R2.EntityZombie.l_(EntityZombie.java:181)
	at net.minecraft.server.v1_6_R2.World.entityJoinedWorld(World.java:1492)
	at net.minecraft.server.v1_6_R2.World.playerJoinedWorld(World.java:1467)
	at net.minecraft.server.v1_6_R2.World.tickEntities(World.java:1336)
	at net.minecraft.server.v1_6_R2.WorldServer.tickEntities(WorldServer.java:517)
	at net.minecraft.server.v1_6_R2.MinecraftServer.t(MinecraftServer.java:571)
	at net.minecraft.server.v1_6_R2.DedicatedServer.t(DedicatedServer.java:239)
	at net.minecraft.server.v1_6_R2.MinecraftServer.s(MinecraftServer.java:481)
	at net.minecraft.server.v1_6_R2.MinecraftServer.run(MinecraftServer.java:413)
	at net.minecraft.server.v1_6_R2.ThreadServerApplication.run(SourceFile:582)
Caused by: java.util.ConcurrentModificationException
	at net.minecraft.server.v1_6_R2.World$1.guard(World.java:47)
	at net.minecraft.server.v1_6_R2.World$1.remove(World.java:41)
	at net.minecraft.server.v1_6_R2.World.removeEntity(World.java:1070)
	at com.hotmail.wolfiemario.rebalancevillagers.RebalanceVillagers.convertVillager(RebalanceVillagers.java:235)
	at com.hotmail.wolfiemario.rebalancevillagers.RebalanceVillagers.onCreatureSpawn(RebalanceVillagers.java:178)
	at sun.reflect.GeneratedMethodAccessor38.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:601)
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
	... 18 more