Exception in server tick loop

http://forum.feed-the-beast.com/threads/crash-report.1559/#post-14990

Description: Exception in server tick loop

java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(Unknown Source)
at java.util.HashMap$ValueIterator.next(Unknown Source)
at ic2.common.AudioManagerClient.onTick(AudioManagerClient.java:104)
at ic2.common.IC2.tickStart(IC2.java:1374)
at cpw.mods.fml.common.SingleIntervalHandler.tickStart(SingleIntervalHandler.java:16)
at cpw.mods.fml.common.FMLCommonHandler.tickStart(FMLCommonHandler.java:116)
at cpw.mods.fml.common.FMLCommonHandler.onPreWorldTick(FMLCommonHandler.java:292)
at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:652)
at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:590)
at bcb.q(IntegratedServer.java:110)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:497)
at fp.run(SourceFile:818)

http://forum.feed-the-beast.com/threads/ftb-crash-and-not-responding.1531/#post-14759
Description: Exception in server tick loop

java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(Unknown Source)
at java.util.HashMap$KeyIterator.next(Unknown Source)
at id.b(ChunkProviderServer.java:298)
at ie.b(WorldServer.java:120)
at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:653)
at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:590)
at bcb.q(IntegratedServer.java:110)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:497)
at fp.run(SourceFile:818)

http://forum.feed-the-beast.com/threads/minecraft-crash-when-loading-new-chunks.1527/#post-14664

java.util.ConcurrentModificationException
    at java.util.ArrayList$Itr.checkForComodification(Unknown Source)
    at java.util.ArrayList$Itr.next(Unknown Source)
    at ib.b(PlayerManager.java:71)
    at ie.b(WorldServer.java:136)
    at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:653)
    at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:590)
    at bcb.q(IntegratedServer.java:110)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:497)
    at fp.run(SourceFile:818)