Hopper: java.lang.ClassCastException: cg cannot be cast to ce

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-23598/

Crash:

java.lang.ClassCastException: cg cannot be cast to ce
	at bx.e(SourceFile:129)
	at ni.b(SourceFile:153)
	at yo.g(SourceFile:61)
	at yo.e(SourceFile:268)
	at yd.v(SourceFile:505)
	at bgt.b(SourceFile:335)
	at avg.a(SourceFile:731)
	at avg.a(SourceFile:120)
	at bfb.b(SourceFile:700)
	at ats.S(SourceFile:686)
	at ats.d(SourceFile:619)
	at net.minecraft.client.main.Main.main(SourceFile:101)

The following is the first clean report made public about this crash:

---- Minecraft Crash Report ----
// Shall we play a game?

Time: 8/4/13 8:33 PM
Description: Reading NBT data

java.lang.ClassCastException: cg cannot be cast to ce
	at bx.e(SourceFile:129)
	at ni.b(SourceFile:153)
	at yo.g(SourceFile:61)
	at yo.e(SourceFile:268)
	at yd.v(SourceFile:505)
	at bgt.b(SourceFile:335)
	at avg.a(SourceFile:731)
	at avg.a(SourceFile:120)
	at bfb.b(SourceFile:700)
	at ats.S(SourceFile:686)
	at ats.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: LONG
	Tag type expected: INT
	Tag name: Duration
Stacktrace:
	at bx.e(SourceFile:129)
	at ni.b(SourceFile:153)
	at yo.g(SourceFile:61)
	at yo.e(SourceFile:268)
	at yd.v(SourceFile:505)
	at bgt.b(SourceFile:335)
	at avg.a(SourceFile:731)
	at avg.a(SourceFile:120)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bdf['dodikabird'/6, l='MpServer', x=-300.70, y=57.62, z=-40.02]]
	Chunk stats: MultiplayerChunkCache: 60
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: World: (-298,4,-31), Chunk: (at 6,0,1 in -19,-2; contains blocks -304,0,-32 to -289,255,-17), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
	Level time: 28231 game time, 15931 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: 2 total; [rx['Dinnerbone'/2, l='MpServer', x=-344.81, y=56.00, z=-47.50], bdf['dodikabird'/6, l='MpServer', x=-300.70, y=57.62, z=-40.02]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at bda.a(SourceFile:284)
	at ats.b(SourceFile:1761)
	at ats.d(SourceFile:628)
	at net.minecraft.client.main.Main.main(SourceFile:101)

-- System Details --
Details:
	Minecraft Version: 1.6.2
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_21, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 109042808 bytes (103 MB) / 363528192 bytes (346 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 21638 (1211728 bytes; 1 MB) allocated, 21638 (1211728 bytes; 1 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 1.6.2
	LWJGL: 2.9.0
	OpenGL: Intel(R) HD Graphics 3000 GL version 3.1.0 - Build 9.17.10.2932, Intel
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Pack: Default
	Current Language: English (UK)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 34 (1904 bytes; 0 MB) allocated, 34 (1904 bytes; 0 MB) used

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-23598/522333/