Plugins not working in specific worlds

Well I've been running this server for a little while, and I have a collection of plugins running at once.

Well I decided to put in "Hero Chat" as a plugin, and it worked in like, all my worlds... except for one. It refused to work in my world "Arcadeworld", which was generated just like all the others. Every other world I had tested in had worked, except that one. I had gotten a funky error when someone would talk,

Code:

2012-02-28 17:22:17 [SEVERE] Could not pass event org.bukkit.event.player.PlayerChatEvent to Herochat
org.bukkit.event.EventException
    at org.bukkit.plugin.java.JavaPluginLoader$103.execute(JavaPluginLoader.java:1026)
    at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:61)
    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:460)
    at net.minecraft.server.NetServerHandler.chat(NetServerHandler.java:749)
    at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:732)
    at net.minecraft.server.Packet3Chat.handle(Packet3Chat.java:33)
    at net.minecraft.server.NetworkManager.b(NetworkManager.java:226)
    at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:100)
    at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:78)
    at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:537)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:435)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:465)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.bukkit.plugin.java.JavaPluginLoader$103.execute(JavaPluginLoader.java:1024)
    ... 11 more
Caused by: java.lang.ArrayIndexOutOfBoundsException: 0
    at net.milkbowl.vault.permission.plugins.Permission_Permissions3.getPrimaryGroup(Permission_Permissions3.java:208)
    at net.milkbowl.vault.chat.Chat.getPrimaryGroup(Chat.java:713)
    at net.milkbowl.vault.chat.Chat.getPrimaryGroup(Chat.java:732)
    at com.dthielke.herochat.StandardChannel.applyFormat(StandardChannel.java:130)
    at com.dthielke.herochat.StandardChannel.processChat(StandardChannel.java:346)
    at com.dthielke.herochat.MessageHandler.handle(MessageHandler.java:129)
    at com.dthielke.herochat.HCPlayerListener.onPlayerChat(HCPlayerListener.java:19)
    ... 16 more

I'd get this... Now first look someone could just say "Hero chat problem take it to them", but in a different world I had recently made, I tried to use another plugin that makes dispensers put minecarts on the tracks directly, doesnt work either (In addition to getting this error when I talk in that world). Instead of putting the minecart on the tracks, it spits it out like a normal dispenser. Note: The other world doesn't do this, in fact that world the minecart system works.

But this appears to be some bug I can't pinpoint. Hero chat is updated, Multiverse is updated, Vault is updated, Bukkit is updated... I just can't seem to find out what the problem is.

My plugins are...
Buildr
ButtonWarp
CaptureThePoints
Citizens
Falsebook(Block;Core;Extra;IC)
CraftBall
Essentials(Protect;Spawn)
iConomy
Jobs
mcMMO
MobArena
MultiInv
Multiverse(Core;Portals;NetherPortals;SignPortals)
Permissions
Questioner
SimpleRegionMarket
Towny
Turnstile
Vault
War
WorldEdit
WorldGuard
SimpleCarts
AllAboard

Anyone got an idea what I could do to fix this? :/ Not sure what's going on here.