Random Crash

---- Minecraft Crash Report ----
// Quite honestly, I wouldn't worry myself about that.

Time: 10/7/13 4:53 PM
Description: Reading NBT data

java.lang.ClassCastException: cf cannot be cast to cj
	at by.d(SourceFile:120)
	at ye.a(SourceFile:439)
	at awy.a(SourceFile:188)
	at axm.a(SourceFile:580)
	at awy.a(SourceFile:168)
	at axp.a(SourceFile:31)
	at axm.a(SourceFile:529)
	at bfe.b(SourceFile:718)
	at atv.S(SourceFile:686)
	at atv.d(SourceFile:619)
	at net.minecraft.client.main.Main.main(SourceFile:101)


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

-- Corrupt NBT tag --
Details:
	Tag type found: INT
	Tag type expected: SHORT
	Tag name: id
Stacktrace:
	at by.d(SourceFile:120)
	at ye.a(SourceFile:439)
	at awy.a(SourceFile:188)
	at axm.a(SourceFile:580)
	at awy.a(SourceFile:168)
	at axp.a(SourceFile:31)
	at axm.a(SourceFile:529)

-- Screen render details --
Details:
	Screen name: axm
	Mouse location: Scaled: (208, 203). Absolute: (625, 353)
	Screen size: Scaled: (427, 321). Absolute: (1280, 962). Scale factor of 3

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bdi['Nektro77'/0, l='MpServer', x=-499.20, y=57.62, z=-1962.12]]
	Chunk stats: MultiplayerChunkCache: 441
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: World: (-512,4,-1960), Chunk: (at 0,0,8 in -32,-123; contains blocks -512,0,-1968 to -497,255,-1953), Region: (-1,-4; contains chunks -32,-128 to -1,-97, blocks -512,0,-2048 to -1,255,-1537)
	Level time: 219039 game time, 6196 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
	Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: false
	Forced entities: 1 total; [bdi['Nektro77'/0, l='MpServer', x=-499.20, y=57.62, z=-1962.12]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at bdd.a(SourceFile:284)
	at atv.b(SourceFile:1761)
	at atv.d(SourceFile:628)
	at net.minecraft.client.main.Main.main(SourceFile:101)

-- System Details --
Details:
	Minecraft Version: 1.6.4
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_11, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 290832432 bytes (277 MB) / 583598080 bytes (556 MB) up to 3817799680 bytes (3640 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx4G
	AABB Pool Size: 19638 (1099728 bytes; 1 MB) allocated, 5 (280 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 1.6.4
	LWJGL: 2.9.0
	OpenGL: ATI Radeon HD 3200 Graphics      GL version 2.1.8787, ATI Technologies Inc.
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Pack: Default
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 109 (6104 bytes; 0 MB) allocated, 32 (1792 bytes; 0 MB) used