Minecraft Crashes While Entering Menus

Minecraft will crash when a menu is entered, like entering the inventory menu, or escape menu. I cannot play 12w50a because of the glitch please fix it in 12w50b.

Here is the crash log:

---- Minecraft Crash Report ----
// Surprise! Haha. Well, this is 

awkward.

Time: 12/13/12 8:15 PM
Description: Unexpected error

java.lang.NoClassDefFoundError: aux
	at net.minecraft.client.Minecraft.l(SourceFile:1273)
	at net.minecraft.client.Minecraft.J(SourceFile:582)
	at net.minecraft.client.Minecraft.run(SourceFile:534)
	at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: aux
	at java.net.URLClassLoader$1.run(Unknown Source)
	at java.net.URLClassLoader$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	... 4 more


A detailed walkthrough of the error, its code path and all known 

details is as follows:
-----------------------------------------------------------------------

----------------

-- Affected level --
Details:
	Level name: MpServer
	

All players: 1 total; [ays['BlueYoshi211'/4, l='MpServer', x=401.50, 

y=14.62, z=376.50]]
	Chunk stats: MultiplayerChunkCache: 441
	Level 

seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	

Level generator options: 
	Level spawn location: World: 

(393,4,371), Chunk: (at 9,0,3 in 24,23; contains blocks 384,0,368 to 

399,255,383), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 

to 511,255,511)
	Level time: 913 game time, 913 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: 5 total; [oy['Chicken'/0, l='MpServer', 

x=351.81, y=13.00, z=386.25], oy['Chicken'/1, l='MpServer', x=351.59, 

y=13.00, z=387.75], oy['Chicken'/2, l='MpServer', x=349.44, y=13.00, 

z=387.38], oy['Chicken'/3, l='MpServer', x=356.44, y=13.00, z=388.47], 

ays['BlueYoshi211'/4, l='MpServer', x=401.50, y=14.62, z=376.50]]
	

Retry entities: 0 total; []
Stacktrace:
	at ayp.a(SourceFile:281)
	

at net.minecraft.client.Minecraft.b(SourceFile:1871)
	at 

net.minecraft.client.Minecraft.run(SourceFile:548)
	at 

java.lang.Thread.run(Unknown Source)

-- System Details --
Details:
	

Minecraft Version: 12w50a
	Operating System: Windows 7 (x86) 

version 6.1
	Java Version: 1.7.0_09, Oracle Corporation
	Java VM 

Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
	

Memory: 336767304 bytes (321 MB) / 519110656 bytes (495 MB) up to 

1037959168 bytes (989 MB)
	JVM Flags: 2 total; -Xms512m -Xmx1024m
	

AABB Pool Size: 2707 (151592 bytes; 0 MB) allocated, 2 (112 bytes; 0 

MB) used
	Suspicious classes: No suspicious classes found.
	

IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	LWJGL: 

2.4.2
	OpenGL: Intel Pineview Platform GL version 1.4.0 - Build 

8.14.10.2117, Intel
	Is Modded: Probably not. Jar signature remains 

and client brand is untouched.
	Type: Client (map_client.txt)
	Texture 

Pack: Default
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 

231 (12936 bytes; 0 MB) allocated, 11 (616 bytes; 0 MB) used