Description: Exception ticking world

java.util.ConcurrentModificationException
	at java.util.HashMap$HashIterator.nextNode(Unknown Source)
	at java.util.HashMap$KeyIterator.next(Unknown Source)
	at net.minecraft.server.management.PlayerChunkMap.func_72693_b(SourceFile:114)
	at net.minecraft.world.WorldServer.func_72835_b(WorldServer.java:222)
	at WorldServerOF.func_72835_b(WorldServerOF.java:37)
	at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:698)
	at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:613)
	at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:240)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:471)
	at java.lang.Thread.run(Unknown Source)