WorldChat Error

11.04 17:29:06 [Server] INFO [WorldChat] Send this to YoshiGenius on http://dev.bukkit.org/ or on the Bukkit Forums!
11.04 17:29:06 [Server] SEVERE at net.minecraft.server.v1_5_R2.NetworkReaderThread.run(SourceFile:94)
11.04 17:29:06 [Server] SEVERE at net.minecraft.server.v1_5_R2.NetworkManager.c(NetworkManager.java:346)
11.04 17:29:06 [Server] SEVERE at net.minecraft.server.v1_5_R2.NetworkManager.i(NetworkManager.java:210)
11.04 17:29:06 [Server] SEVERE at net.minecraft.server.v1_5_R2.Packet3Chat.handle(Packet3Chat.java:44)
11.04 17:29:06 [Server] SEVERE at net.minecraft.server.v1_5_R2.PlayerConnection.a(PlayerConnection.java:840)
11.04 17:29:06 [Server] SEVERE at net.minecraft.server.v1_5_R2.PlayerConnection.chat(PlayerConnection.java:890)
11.04 17:29:06 [Server] SEVERE at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:459)
11.04 17:29:06 [Server] SEVERE at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
11.04 17:29:06 [Server] SEVERE at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
11.04 17:29:06 [Server] SEVERE at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
11.04 17:29:06 [Server] SEVERE at java.lang.reflect.Method.invoke(Method.java:601)
11.04 17:29:06 [Server] SEVERE at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
11.04 17:29:06 [Server] SEVERE at sun.reflect.GeneratedMethodAccessor170.invoke(Unknown Source)
11.04 17:29:06 [Server] SEVERE at com.yoshigenius.plugins.worldchat.WorldChat.onChat(WorldChat.java:32)
11.04 17:29:06 [Server] SEVERE at java.util.HashMap$KeyIterator.next(HashMap.java:928)
11.04 17:29:06 [Server] SEVERE at java.util.HashMap$HashIterator.nextEntry(HashMap.java:894)
11.04 17:29:06 [Server] SEVERE java.util.ConcurrentModificationException
11.04 17:29:06 [Server] INFO [WorldChat] Something went wrong!