Hopper: java.lang.SecurityException: SHA1 digest error for avg.class

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-194547/

Crash:

java.lang.SecurityException: SHA1 digest error for avg.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$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at blt.a(SourceFile:259)
	at awe.a(SourceFile:69)
	at blt.a(SourceFile:503)
	at awe.d(SourceFile:128)
	at awe.m(SourceFile:107)

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

---- Minecraft Crash Report ----
// Oh - I know what I did wrong!

Time: 9/19/13 10:18 PM
Description: Updating screen events

java.lang.SecurityException: SHA1 digest error for avg.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$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at blt.a(SourceFile:259)
	at awe.a(SourceFile:69)
	at blt.a(SourceFile:503)
	at awe.d(SourceFile:128)
	at awe.m(SourceFile:107)
	at atv.k(SourceFile:1158)
	at atv.S(SourceFile:663)
	at atv.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 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$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at blt.a(SourceFile:259)
	at awe.a(SourceFile:69)
	at blt.a(SourceFile:503)
	at awe.d(SourceFile:128)
	at awe.m(SourceFile:107)

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

-- System Details --
Details:
	Minecraft Version: 1.6.4
	Operating System: Windows Vista (x86) version 6.0
	Java Version: 1.7.0_40, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 21679224 bytes (20 MB) / 97955840 bytes (93 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: reis
	LWJGL: 2.9.0
	OpenGL: AMD Radeon HD 6800 Series GL version 4.2.12217 Compatibility Profile Context 12.104.0.0, ATI Technologies Inc.
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Pack: Soartex_Fanver.zip
	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-194547/12521076/