Como resolver esse problema no minecraft crash?

---- Minecraft Crash Report ----

// There are four lights!

Time: 26/05/13 18:47

Description: Exception in server tick loop

java.util.ConcurrentModificationException

at java.util.ArrayDeque$DeqIterator.next(Unknown Source)

at ic2.core.IC2.tickStart(IC2.java:1619)

at cpw.mods.fml.common.SingleIntervalHandler.tickStart(SingleIntervalHandler.java:16)

at cpw.mods.fml.common.FMLCommonHandler.tickStart(FMLCommonHandler.java:119)

at cpw.mods.fml.common.FMLCommonHandler.onPreWorldTick(FMLCommonHandler.java:295)

at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:664)

at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:599)

at bdz.q(IntegratedServer.java:170)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:497)

at fy.run(SourceFile:849)

A detailed walkthrough of the error, its code path and all known details is as follows:

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Quando eu ando para muito longe da esse problema já instalei 2 vezes e n deu certo continua assim