Hopper: java.lang.NoClassDefFoundError: paulscode/sound/SoundSystemException

java.lang.NoClassDefFoundError: paulscode/sound/SoundSystemException
	at btc.<init>(SourceFile:63)
	at azd.Z(SourceFile:396)

---- Minecraft Crash Report ----
// Shall we play a game?

Time: 25/10/13 15:28
Description: Initializing game

java.lang.NoClassDefFoundError: paulscode/sound/SoundSystemException
	at btc.<init>(SourceFile:63)
	at azd.Z(SourceFile:396)
	at azd.e(SourceFile:689)
	at net.minecraft.client.main.Main.main(SourceFile:103)
Caused by: java.lang.ClassNotFoundException: paulscode.sound.SoundSystemException
	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)
	... 4 more


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

-- Head --
Stacktrace:
	at btc.<init>(SourceFile:63)
	at azd.Z(SourceFile:396)

-- Initialization --
Details:
Stacktrace:
	at azd.e(SourceFile:689)
	at net.minecraft.client.main.Main.main(SourceFile:103)

-- System Details --
Details:
	Minecraft Version: 1.7.2
	Operating System: Windows 8 (x86) version 6.2
	Java Version: 1.7.0_45, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 2905176 bytes (2 MB) / 26808320 bytes (25 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
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 1.7.2
	LWJGL: 2.9.0
	OpenGL: AMD Radeon HD 7670M GL version 4.2.11764 Compatibility Profile Context, ATI Technologies Inc.
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: []
	Current Language: ~~ERROR~~ NullPointerException: null
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: ~~ERROR~~ NullPointerException: null
	Anisotropic Filtering: Off (1)