Hopper: java.lang.NullPointerException

java.lang.NullPointerException
	at alr.a(SourceFile:143)
	at alr.e(SourceFile:126)
	at net.minecraft.server.MinecraftServer.R(SourceFile:856)
	at ka.a(SourceFile:594)
	at do.a(SourceFile:30)
	at cn.b(SourceFile:64)
	at ka.e(SourceFile:60)

---- Minecraft Crash Report ----
// I feel sad now :(

Time: 18.09.13 13:14
Description: Ticking memory connection

java.lang.NullPointerException
	at alr.a(SourceFile:143)
	at alr.e(SourceFile:126)
	at net.minecraft.server.MinecraftServer.R(SourceFile:856)
	at ka.a(SourceFile:594)
	at do.a(SourceFile:30)
	at cn.b(SourceFile:64)
	at ka.e(SourceFile:60)
	at kd.b(SourceFile:37)
	at blc.b(SourceFile:84)
	at net.minecraft.server.MinecraftServer.t(SourceFile:489)
	at net.minecraft.server.MinecraftServer.s(SourceFile:406)
	at bkz.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:340)
	at hi.run(SourceFile:583)


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

-- Head --
Stacktrace:
	at alr.a(SourceFile:143)
	at alr.e(SourceFile:126)
	at net.minecraft.server.MinecraftServer.R(SourceFile:856)
	at ka.a(SourceFile:594)
	at do.a(SourceFile:30)
	at cn.b(SourceFile:64)
	at ka.e(SourceFile:60)

-- Ticking connection --
Details:
	Connection: ka@df7af
Stacktrace:
	at kd.b(SourceFile:37)
	at blc.b(SourceFile:84)
	at net.minecraft.server.MinecraftServer.t(SourceFile:489)
	at net.minecraft.server.MinecraftServer.s(SourceFile:406)
	at bkz.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:340)
	at hi.run(SourceFile:583)

-- System Details --
Details:
	Minecraft Version: 1.6.4
	Operating System: Windows XP (x86) version 5.1
	Java Version: 1.7.0_40, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 73080264 bytes (69 MB) / 518979584 bytes (494 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 5068 (283808 bytes; 0 MB) allocated, 4731 (264936 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 1, tallocated: 63
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 1309 (73304 bytes; 0 MB) allocated, 1226 (68656 bytes; 0 MB) used
	Player Count: 0 / 8; []
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.