---- Minecraft Crash Report ----
// Why is it breaking :(

Time: 1/08/14 2:02 AM
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 qi.a(SourceFile:163)
	at net.minecraft.server.MinecraftServer.y(SourceFile:614)
	at net.minecraft.server.MinecraftServer.x(SourceFile:530)
	at cxc.x(SourceFile:155)
	at net.minecraft.server.MinecraftServer.run(SourceFile:446)
	at java.lang.Thread.run(Unknown Source)


A detailed walkthrough of the error, its code path and all known details is as follows:
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-- System Details --
Details:
	Minecraft Version: 14w31a
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_55, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
	Memory: 182857064 bytes (174 MB) / 582066176 bytes (555 MB) up to 1037959168 bytes (989 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
	Profiler Position: N/A (disabled)
	Player Count: 1 / 8; [qr['tragictryhard'/227, l='world', x=-1119.97, y=63.00, z=-103.66]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.