Exception in thread: Unknown constant tag 0 in class file vi

[learnerofskills]

Hello. I'm having an issue launching my Minecraft client.

Vanilla Minecraft works fine, So does Minecraft 1.0 after downgrading it. After installing the Tekkit Pack however, Minecraft crashes after logging in, and this error occurs:

Exception in thread "Thread-3" java.lang.ClassFormatError: Unknown constant tag 0 in class file vi

    at java.lang.ClassLoader.defineClass1(Native Method)

    at java.lang.ClassLoader.defineClass(ClassLoader.java:791)

    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)

    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)

    at java.net.URLClassLoader.access$100(URLClassLoader.java:71)

    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)

    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)

    at java.security.AccessController.doPrivileged(Native Method)

    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)

    at java.lang.ClassLoader.loadClass(ClassLoader.java:423)

    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)

    at java.lang.ClassLoader.defineClass1(Native Method)

    at java.lang.ClassLoader.defineClass(ClassLoader.java:791)

    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)

    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)

    at java.net.URLClassLoader.access$100(URLClassLoader.java:71)

    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)

    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)

    at java.security.AccessController.doPrivileged(Native Method)

    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)

    at java.lang.ClassLoader.loadClass(ClassLoader.java:423)

    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)

    at net.minecraft.client.MinecraftApplet.init(SourceFile:33)

    at net.minecraft.Launcher.replace(Launcher.java:143)

    at net.minecraft.Launcher$1.run(Launcher.java:87)

Some information about my system... I'm running Arch linux x86_64.

I have the newest java7 jre and jdk installed.

Any help you can give me would be appreciated. Thank You.