Hopper: java.lang.ClassFormatError: Truncated class file

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-3120/

Crash:

java.lang.ClassFormatError: Truncated class file
	at java.lang.ClassLoader.findBootstrapClass(Native Method)
	at java.lang.ClassLoader.findBootstrapClassOrNull(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at auw.A_(SourceFile:65)
	at awb.a(SourceFile:94)
	at ats.a(SourceFile:550)
	at auy.a(SourceFile:257)
	at awb.a(SourceFile:69)
	at auy.a(SourceFile:302)
	at awb.d(SourceFile:128)
	at awb.m(SourceFile:107)

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

---- Minecraft Crash Report ----
// Don't be sad, have a hug! <3

Time: 8/30/13 8:09 PM
Description: Updating screen events

java.lang.ClassFormatError: Truncated class file
	at java.lang.ClassLoader.findBootstrapClass(Native Method)
	at java.lang.ClassLoader.findBootstrapClassOrNull(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at auw.A_(SourceFile:65)
	at awb.a(SourceFile:94)
	at ats.a(SourceFile:550)
	at auy.a(SourceFile:257)
	at awb.a(SourceFile:69)
	at auy.a(SourceFile:302)
	at awb.d(SourceFile:128)
	at awb.m(SourceFile:107)
	at ats.k(SourceFile:1158)
	at ats.S(SourceFile:663)
	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:
---------------------------------------------------------------------------------------

-- Head --
Stacktrace:
	at java.lang.ClassLoader.findBootstrapClass(Native Method)
	at java.lang.ClassLoader.findBootstrapClassOrNull(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at auw.A_(SourceFile:65)
	at awb.a(SourceFile:94)
	at ats.a(SourceFile:550)
	at auy.a(SourceFile:257)
	at awb.a(SourceFile:69)
	at auy.a(SourceFile:302)
	at awb.d(SourceFile:128)
	at awb.m(SourceFile:107)

-- Affected screen --
Details:
	Screen name: auw
Stacktrace:
	at ats.k(SourceFile:1158)
	at ats.S(SourceFile:663)
	at ats.d(SourceFile:619)
	at net.minecraft.client.main.Main.main(SourceFile:101)

-- System Details --
Details:
	Minecraft Version: 1.6.2
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_17, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
	Memory: 234099736 bytes (223 MB) / 348676096 bytes (332 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 2588 (144928 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 3, tallocated: 63
	Launched Version: 1.6.2
	LWJGL: 2.9.0
	OpenGL: GeForce 8400GS/PCIe/SSE2 GL version 3.3.0, NVIDIA Corporation
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Pack: Default
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: ~~ERROR~~ NullPointerException: null

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-3120/6826065/