[MC-4830] Minecraft crashing

Hi,
I tried updating minecraft to the newest version today and if I hit "E" while in any world to open to open the inventory, the game crashes with this error. I did backup the folder before making any changes. Text file is also attached.
Please let me know how I can get back to playing again.
Thanks,
David
Minecraft has crashed!      
      ----------------------      

Minecraft has stopped running because it encountered a problem; Unexpected error

A full error report has been saved to C:\Users\Brian\AppData\Roaming\.minecraft\crash-reports\crash-2012-12-16_16.32.48-client.txt - Please include a copy of that file (Not this screen!) if you report this crash to anyone; without it, they will not be able to help fix the crash :(



--- BEGIN ERROR REPORT 4f9a443c --------
Full report at:
C:\Users\Brian\AppData\Roaming\.minecraft\crash-reports\crash-2012-12-16_16.32.48-client.txt
Please show that file to Mojang, NOT just this screen!

Generated 12/16/12 4:32 PM

-- Head --
Stacktrace:
	at sun.security.util.ManifestEntryVerifier.verify(Unknown Source)
	at java.util.jar.JarVerifier.processEntry(Unknown Source)
	at java.util.jar.JarVerifier.update(Unknown Source)
	at java.util.jar.JarVerifier$VerifierStream.read(Unknown Source)
	at sun.misc.Resource.getBytes(Unknown Source)
	at java.net.URLClassLoader.defineClass(Unknown Source)
	at java.net.URLClassLoader.access$100(Unknown Source)
	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)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [ays['Player'/236, l='MpServer', x=-140.81, y=67.62, z=28.11]]
	Chunk stats: MultiplayerChunkCache: 441
	Level seed: 0
	Level generator: ID 00 - default, ver 1. Features enabled: false
	Level generator options: 
	Level spawn location: World: (-200,64,-60), Chunk: (at 8,4,4 in -13,-4; contains blocks -208,0,-64 to -193,255,-49), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
	Level time: 70211 game time, 70211 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: 38 total; [ph['Squid'/205, l='MpServer', x=-77.97, y=46.31, z=-27.56], ph['Squid'/204, l='MpServer', x=-79.34, y=45.19, z=-31.94], ph['Squid'/206, l='MpServer', x=-77.50, y=48.31, z=-23.75], pe['Sheep'/152, l='MpServer', x=-191.43, y=69.00, z=6.81], pe['Sheep'/153, l='MpServer', x=-176.50, y=83.00, z=10.78], pe['Sheep'/157, l='MpServer', x=-172.81, y=72.00, z=14.69], pe['Sheep'/158, l='MpServer', x=-170.50, y=83.00, z=5.53], oy['Chicken'/159, l='MpServer', x=-159.61, y=62.36, z=39.28], ph['Squid'/212, l='MpServer', x=-80.81, y=47.38, z=47.66], oy['Chicken'/148, l='MpServer', x=-188.47, y=72.00, z=-50.44], ow['Bat'/208, l='MpServer', x=-69.02, y=29.86, z=31.55], ow['Bat'/149, l='MpServer', x=-182.39, y=22.84, z=-22.02], ow['Bat'/209, l='MpServer', x=-80.59, y=23.92, z=36.44], ph['Squid'/210, l='MpServer', x=-83.44, y=47.16, z=39.91], ow['Bat'/150, l='MpServer', x=-181.33, y=47.32, z=-23.45], ph['Squid'/211, l='MpServer', x=-81.22, y=48.34, z=43.13], ow['Bat'/151, l='MpServer', x=-169.54, y=42.51, z=-5.75], ow['Bat'/163, l='MpServer', x=-163.55, y=20.27, z=104.63], px['item.item.egg'/162, l='MpServer', x=-163.19, y=60.13, z=57.72], oy['Chicken'/161, l='MpServer', x=-162.41, y=62.43, z=56.44], px['item.item.egg'/160, l='MpServer', x=-164.13, y=58.13, z=43.28], oy['Chicken'/119, l='MpServer', x=-216.50, y=83.00, z=48.50], ow['Bat'/186, l='MpServer', x=-76.51, y=33.74, z=19.14], ph['Squid'/187, l='MpServer', x=-79.50, y=46.34, z=39.75], ow['Bat'/184, l='MpServer', x=-83.58, y=32.07, z=17.35], ow['Bat'/185, l='MpServer', x=-80.97, y=26.10, z=28.03], ays['Player'/236, l='MpServer', x=-140.81, y=67.62, z=28.11], ph['Squid'/188, l='MpServer', x=-78.19, y=53.38, z=71.91], ow['Bat'/178, l='MpServer', x=-132.25, y=21.38, z=23.31], ow['Bat'/179, l='MpServer', x=-99.88, y=34.10, z=10.31], oy['Chicken'/176, l='MpServer', x=-112.53, y=62.49, z=1.47], px['item.item.egg'/177, l='MpServer', x=-112.13, y=59.13, z=3.03], ow['Bat'/182, l='MpServer', x=-92.61, y=29.03, z=13.78], ow['Bat'/183, l='MpServer', x=-91.00, y=28.10, z=35.75], oy['Chicken'/121, l='MpServer', x=-218.50, y=83.00, z=48.24], ph['Squid'/180, l='MpServer', x=-106.09, y=56.00, z=16.19], oy['Chicken'/120, l='MpServer', x=-217.50, y=83.00, z=49.50], ow['Bat'/181, l='MpServer', x=-106.05, y=24.94, z=29.96]]
	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: 12w50b
	Operating System: Windows Vista (x86) version 6.0
	Java Version: 1.7.0_09, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
	Memory: 315683984 bytes (301 MB) / 519110656 bytes (495 MB) up to 1037959168 bytes (989 MB)
	JVM Flags: 2 total; -Xms512m -Xmx1024m
	AABB Pool Size: 9253 (518168 bytes; 0 MB) allocated, 2 (112 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 3, tallocated: 63
	LWJGL: 2.4.2
	OpenGL: Intel 965/963 Graphics Media Accelerator GL version 1.5.0 - Build 7.14.10.1409, 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: 5428 (303968 bytes; 0 MB) allocated, 20 (1120 bytes; 0 MB) used

java.lang.SecurityException: SHA1 digest error for aux.class
	at sun.security.util.ManifestEntryVerifier.verify(Unknown Source)
	at java.util.jar.JarVerifier.processEntry(Unknown Source)
	at java.util.jar.JarVerifier.update(Unknown Source)
	at java.util.jar.JarVerifier$VerifierStream.read(Unknown Source)
	at sun.misc.Resource.getBytes(Unknown Source)
	at java.net.URLClassLoader.defineClass(Unknown Source)
	at java.net.URLClassLoader.access$100(Unknown Source)
	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)
	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)
--- END ERROR REPORT 46d1feea ----------