Was steht denn im Crash Log?
Description: Initializing game
java.lang.NoClassDefFoundError: javax/vecmath/Vector3f
at net.minecraft.client.renderer.block.model.ItemTransformVec3f$Deserializer.<clinit>(ItemTransformVec3f.java:31)
at net.minecraft.client.renderer.block.model.ModelBlock.<clinit>(ModelBlock.java:31)
at net.minecraft.client.resources.model.ModelBakery.<clinit>(ModelBakery.java:800)
at net.minecraft.client.resources.model.ModelManager.onResourceManagerReload(ModelManager.java:25)
at net.minecraft.client.resources.SimpleReloadableResourceManager.registerReloadListener(SimpleReloadableResourceManager.java:121)
at net.minecraft.client.Minecraft.startGame(Minecraft.java:530)
at net.minecraft.client.Minecraft.run(Minecraft.java:383)
at net.minecraft.client.main.Main.main(Main.java:114)
Caused by: java.lang.ClassNotFoundException: javax.vecmath.Vector3f
at java.net.URLClassLoader$1.run(URLClassLoader.java:372)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 8 more