Hopper: java.lang.ClassCastException: cf cannot be cast to bx

java.lang.ClassCastException: cf cannot be cast to bx
	at by.c(SourceFile:111)
	at sr.a(SourceFile:186)
	at nn.f(SourceFile:1062)
	at abn.a(SourceFile:116)
	at abn.g(SourceFile:92)
	at sz.l_(SourceFile:75)
	at nn.V(SourceFile:1165)
	at abw.a(SourceFile:1347)
	at js.a(SourceFile:479)
	at abw.g(SourceFile:1327)
	at abw.a(SourceFile:1386)
	at js.a(SourceFile:479)
	at abw.g(SourceFile:1327)
	at abw.a(SourceFile:1386)
	at js.a(SourceFile:479)
	at abw.g(SourceFile:1327)
	at abw.h(SourceFile:1234)
	at js.h(SourceFile:364)
	at net.minecraft.server.MinecraftServer.t(SourceFile:471)
	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)

---- Minecraft Crash Report ----
// Don't do that.

Time: 19/09/13 16:58
Description: Reading NBT data

java.lang.ClassCastException: cf cannot be cast to bx
	at by.c(SourceFile:111)
	at sr.a(SourceFile:186)
	at nn.f(SourceFile:1062)
	at abn.a(SourceFile:116)
	at abn.g(SourceFile:92)
	at sz.l_(SourceFile:75)
	at nn.V(SourceFile:1165)
	at abw.a(SourceFile:1347)
	at js.a(SourceFile:479)
	at abw.g(SourceFile:1327)
	at abw.a(SourceFile:1386)
	at js.a(SourceFile:479)
	at abw.g(SourceFile:1327)
	at abw.a(SourceFile:1386)
	at js.a(SourceFile:479)
	at abw.g(SourceFile:1327)
	at abw.h(SourceFile:1234)
	at js.h(SourceFile:364)
	at net.minecraft.server.MinecraftServer.t(SourceFile:471)
	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:
---------------------------------------------------------------------------------------

-- Corrupt NBT tag --
Details:
	Tag type found: INT
	Tag type expected: BYTE
	Tag name: Time
Stacktrace:
	at by.c(SourceFile:111)
	at sr.a(SourceFile:186)

-- Entity being loaded --
Details:
	Entity Type: FallingSand (sr)
	Entity ID: 428
	Entity Name: Falling Block
	Entity's Exact location: 24.00, 56.00, 255.00
	Entity's Block location: World: (24,56,255), Chunk: (at 8,3,15 in 1,15; contains blocks 16,0,240 to 31,255,255), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Entity's Momentum: 0.00, 0.00, 0.00
	Immitating block ID: 66
	Immitating block data: 0
Stacktrace:
	at nn.f(SourceFile:1062)
	at abn.a(SourceFile:116)
	at abn.g(SourceFile:92)
	at sz.l_(SourceFile:75)
	at nn.V(SourceFile:1165)
	at abw.a(SourceFile:1347)
	at js.a(SourceFile:479)
	at abw.g(SourceFile:1327)
	at abw.a(SourceFile:1386)
	at js.a(SourceFile:479)
	at abw.g(SourceFile:1327)
	at abw.a(SourceFile:1386)
	at js.a(SourceFile:479)
	at abw.g(SourceFile:1327)

-- Entity being ticked --
Details:
	Entity Type: MinecartRideable (sy)
	Entity ID: 233
	Entity Name: entity.MinecartRideable.name
	Entity's Exact location: 24.50, 55.50, 255.49
	Entity's Block location: World: (24,55,255), Chunk: (at 8,3,15 in 1,15; contains blocks 16,0,240 to 31,255,255), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Entity's Momentum: 0.00, -0.00, 0.00
Stacktrace:
	at abw.h(SourceFile:1234)
	at js.h(SourceFile:364)

-- Affected level --
Details:
	Level name: New World
	All players: 1 total; [jv['Molemyster'/399, l='New World', x=22.58, y=66.59, z=249.11]]
	Chunk stats: ServerChunkCache: 646 Drop: 0
	Level seed: -1005553066
	Level generator: ID 00 - default, ver 1. Features enabled: true
	Level generator options: 
	Level spawn location: World: (-24,64,256), Chunk: (at 8,4,0 in -2,16; contains blocks -32,0,256 to -17,255,271), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
	Level time: 7321 game time, 7321 day time
	Level dimension: 0
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 158854 (now: false), thunder time: 113285 (now: false)
	Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true
Stacktrace:
	at net.minecraft.server.MinecraftServer.t(SourceFile:471)
	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 7 (amd64) version 6.1
	Java Version: 1.7.0_15, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 258563520 bytes (246 MB) / 481034240 bytes (458 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 4740 (265440 bytes; 0 MB) allocated, 2603 (145768 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 3, tallocated: 63
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 1628 (91168 bytes; 0 MB) allocated, 734 (41104 bytes; 0 MB) used
	Player Count: 1 / 8; [jv['Molemyster'/399, l='New World', x=22.58, y=66.59, z=249.11]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.