Hopper: java.lang.ClassCastException: zk cannot be cast to bdt

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-465860/

Crash:

java.lang.ClassCastException: zk cannot be cast to bdt
	at bdr.a(SourceFile:176)
	at bdd.a(SourceFile:355)
	at bcd.d(SourceFile:243)
	at bdr.d(SourceFile:490)
	at bcd.k(SourceFile:211)

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

---- Minecraft Crash Report ----
// Everything's going to plan. No, really, that was supposed to happen.

Time: 26.10.13 11:40
Description: Updating screen events

java.lang.ClassCastException: zk cannot be cast to bdt
	at bdr.a(SourceFile:176)
	at bdd.a(SourceFile:355)
	at bcd.d(SourceFile:243)
	at bdr.d(SourceFile:490)
	at bcd.k(SourceFile:211)
	at azd.o(SourceFile:1303)
	at azd.ad(SourceFile:753)
	at azd.e(SourceFile:704)
	at net.minecraft.client.main.Main.main(SourceFile:103)


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

-- Head --
Stacktrace:
	at bdr.a(SourceFile:176)
	at bdd.a(SourceFile:355)
	at bcd.d(SourceFile:243)
	at bdr.d(SourceFile:490)
	at bcd.k(SourceFile:211)

-- Affected screen --
Details:
	Screen name: bdr

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bje['leo_noah_08'/142983, l='MpServer', x=-137,32, y=5,62, z=-428,58]]
	Chunk stats: MultiplayerChunkCache: 285, 285
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: World: (-150,4,-479), Chunk: (at 10,0,1 in -10,-30; contains blocks -160,0,-480 to -145,255,-465), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
	Level time: 3069 game time, 3069 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: 13 total; [va['Schwein'/213527, l='MpServer', x=-170,25, y=4,00, z=-419,09], va['Schwein'/213525, l='MpServer', x=-154,50, y=4,00, z=-432,50], va['Schwein'/213528, l='MpServer', x=-149,19, y=4,00, z=-431,56], vb['Schaf'/213534, l='MpServer', x=-79,78, y=4,00, z=-479,78], vb['Schaf'/213537, l='MpServer', x=-78,19, y=4,00, z=-478,19], vb['Schaf'/213540, l='MpServer', x=-77,22, y=4,00, z=-481,22], vb['Schaf'/213542, l='MpServer', x=-78,81, y=4,00, z=-482,81], va['Schwein'/213544, l='MpServer', x=-68,03, y=4,00, z=-492,03], us['Huhn'/213547, l='MpServer', x=-129,09, y=4,00, z=-426,22], bje['leo_noah_08'/142983, l='MpServer', x=-137,32, y=5,62, z=-428,58], us['Huhn'/213549, l='MpServer', x=-123,59, y=4,00, z=-423,59], us['Huhn'/213548, l='MpServer', x=-128,59, y=4,00, z=-438,44], us['Huhn'/213550, l='MpServer', x=-131,56, y=4,00, z=-422,44]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at biz.a(SourceFile:284)
	at azd.b(SourceFile:1951)
	at azd.e(SourceFile:713)
	at net.minecraft.client.main.Main.main(SourceFile:103)

-- System Details --
Details:
	Minecraft Version: 1.7.2
	Operating System: Windows XP (x86) version 5.1
	Java Version: 1.7.0_45, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 154689120 bytes (147 MB) / 282009600 bytes (268 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 897 (50232 bytes; 0 MB) allocated, 2 (112 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
	Launched Version: 1.7.2
	LWJGL: 2.9.0
	OpenGL: ATI FireGL V3350 GL version 2.1.8501 FireGL Release, ATI Technologies Inc.
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: []
	Current Language: Deutsch (Deutschland)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 208 (11648 bytes; 0 MB) allocated, 18 (1008 bytes; 0 MB) used
	Anisotropic Filtering: Off (1)

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-465860/21671850/