I am getting the error below in the server console, any idea?
This error is since playing 1.0.7
2014-01-24 19:38:33 [INFO] [Minecraft-Server] An unknown error occurred while attempting to perform this command
2014-01-24 19:38:33 [INFO] [STDERR] java.lang.IllegalArgumentException: Comparison method violates its general contract!
2014-01-24 19:38:33 [INFO] [STDERR] at java.util.ComparableTimSort.mergeHi(ComparableTimSort.java:862)
2014-01-24 19:38:33 [INFO] [STDERR] at java.util.ComparableTimSort.mergeAt(ComparableTimSort.java:479)
2014-01-24 19:38:33 [INFO] [STDERR] at java.util.ComparableTimSort.mergeForceCollapse(ComparableTimSort.java:418)
2014-01-24 19:38:33 [INFO] [STDERR] at java.util.ComparableTimSort.sort(ComparableTimSort.java:218)
2014-01-24 19:38:33 [INFO] [STDERR] at java.util.Arrays.sort(Arrays.java:1244)
2014-01-24 19:38:33 [INFO] [STDERR] at java.util.Collections.sort(Collections.java:166)
2014-01-24 19:38:33 [INFO] [STDERR] at net.minecraft.command.CommandHelp.func_71534_d(SourceFile:74)
2014-01-24 19:38:33 [INFO] [STDERR] at net.minecraft.command.CommandHelp.func_71515_b(SourceFile:36)
2014-01-24 19:38:33 [INFO] [STDERR] at net.minecraft.command.CommandHandler.func_71556_a(CommandHandler.java:88)
2014-01-24 19:38:33 [INFO] [STDERR] at net.minecraft.server.dedicated.DedicatedServer.func_71333_ah(DedicatedServer.java:315)
2014-01-24 19:38:33 [INFO] [STDERR] at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:277)
2014-01-24 19:38:33 [INFO] [STDERR] at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:587)
2014-01-24 19:38:33 [INFO] [STDERR] at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:484)
2014-01-24 19:38:33 [INFO] [STDERR] at net.minecraft.server.ThreadMinecraftServer.run(SourceFile:583)
2014-01-24 19:38:38 [INFO] [STDERR] java.util.ConcurrentModificationException
2014-01-24 19:38:38 [INFO] [STDERR] at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429)
2014-01-24 19:38:38 [INFO] [STDERR] at java.util.HashMap$ValueIterator.next(HashMap.java:1458)
2014-01-24 19:38:38 [INFO] [STDERR] at net.minecraft.nbt.NBTTagCompound.func_74734_a(SourceFile:25)
2014-01-24 19:38:38 [INFO] [STDERR] at net.minecraft.nbt.NBTBase.func_74731_a(SourceFile:119)
2014-01-24 19:38:38 [INFO] [STDERR] at net.minecraft.nbt.CompressedStreamTools.func_74800_a(CompressedStreamTools.java:140)
2014-01-24 19:38:38 [INFO] [STDERR] at net.minecraft.world.chunk.storage.AnvilChunkLoader.func_75821_a(AnvilChunkLoader.java:198)
2014-01-24 19:38:38 [INFO] [STDERR] at net.minecraft.world.chunk.storage.AnvilChunkLoader.func_75814_c(AnvilChunkLoader.java:184)
2014-01-24 19:38:38 [INFO] [STDERR] at net.minecraft.world.storage.ThreadedFileIOBase.func_75736_b(SourceFile:30)
2014-01-24 19:38:38 [INFO] [STDERR] at net.minecraft.world.storage.ThreadedFileIOBase.run(SourceFile:23)
2014-01-24 19:38:38 [INFO] [STDERR] at java.lang.Thread.run(Thread.java:744)