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Loading URL: file:/E:/Games/MultiMC/instances/1.5.1/minecraft/bin/minecraft.jar
Loading URL: file:/E:/Games/MultiMC/instances/1.5.1/minecraft/bin/lwjgl.jar
Loading URL: file:/E:/Games/MultiMC/instances/1.5.1/minecraft/bin/lwjgl_util.jar
Loading URL: file:/E:/Games/MultiMC/instances/1.5.1/minecraft/bin/jinput.jar
Loading natives...
java.lang.SecurityException: Invalid signature file digest for Manifest main attributes
at sun.security.util.SignatureFileVerifier.processImpl(Unknown Source)
at sun.security.util.SignatureFileVerifier.process(Unknown Source)
at java.util.jar.JarVerifier.processEntry(Unknown Source)
at java.util.jar.JarVerifier.update(Unknown Source)
at java.util.jar.JarFile.initializeVerifier(Unknown Source)
at java.util.jar.JarFile.getInputStream(Unknown Source)
at sun.misc.URLClassPath$JarLoader$2.getInputStream(Unknown Source)
at sun.misc.Resource.cachedInputStream(Unknown Source)
at sun.misc.Resource.getByteBuffer(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 java.lang.ClassLoader.loadClass(Unknown Source)
at MultiMCLauncher.main(MultiMCLauncher.java:157)
Minecraft exited with code 4.
Minecraft has crashed!
If I have only Forge (676) loaded and I add any of the following mods I get the above error: IC2, Inventory Tweaks, CodeChickenCore, PowerCrystal Core, EE3, BC, or Natura. This error and crash happens loading them solo with only Forge installed otherwise. That list of crashing mods represents 75% of the mods I've tried to get working with 1.5.1 under MultiMC. So far only Ars Magicka, NEI and Tinker's Construct seem to want to behave at all, as they are all cooperating together. Everything else bottoms out MC running even solo.