je ne peux pas démarrer Forge ! (au lancement Minecraft s'ouvre et se ferme puis plus rien !)
voici une partie de l'érreur qui me semble la plus correcte:
Caused by: java.lang.NoClassDefFoundError: net/minecraft/client/gui/GuiMainMenu
Caused by: java.lang.ClassNotFoundException: net.minecraft.client.gui.GuiMainMenu

Voici l’erreur (entière) :
janv. 30, 2015 7:07:24 PM net.minecraft.launchwrapper.LogWrapper log
INFOS: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker
janv. 30, 2015 7:07:24 PM net.minecraft.launchwrapper.LogWrapper log
INFOS: Using primary tweak class name cpw.mods.fml.common.launcher.FMLTweaker
janv. 30, 2015 7:07:24 PM net.minecraft.launchwrapper.LogWrapper log
INFOS: Calling tweak class cpw.mods.fml.common.launcher.FMLTweaker
2015-01-30 19:07:24 [INFOS] [ForgeModLoader] Forge Mod Loader version 6.4.49.965 for Minecraft 1.6.4 loading
2015-01-30 19:07:24 [INFOS] [ForgeModLoader] Java is OpenJDK 64-Bit Server VM, version 1.7.0_75, running on Linux:amd64:3.16.0-29-generic, installed at /usr/lib/jvm/java-7-openjdk-amd64/jre
2015-01-30 19:07:24 [INFOS] [ForgeModLoader] Loading tweaker optifine.OptiFineForgeTweaker from OptiFine_1.7.10_HD_U_A4.jar
2015-01-30 19:07:24 [INFOS] [ForgeModLoader] Loading tweaker shadersmodcore.loading.SMCTweaker from ShadersModCore-v2.3.18-mc1.7.10-f1179.jar
2015-01-30 19:07:24 [INFOS] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
2015-01-30 19:07:24 [INFOS] [ForgeModLoader] Loading tweak class name optifine.OptiFineForgeTweaker
2015-01-30 19:07:24 [INFOS] [ForgeModLoader] Loading tweak class name shadersmodcore.loading.SMCTweaker
2015-01-30 19:07:24 [INFOS] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker
2015-01-30 19:07:24 [INFOS] [ForgeModLoader] Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
2015-01-30 19:07:24 [INFOS] [ForgeModLoader] Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
2015-01-30 19:07:24 [INFOS] [ForgeModLoader] Calling tweak class optifine.OptiFineForgeTweaker
2015-01-30 19:07:24 [INFOS] [STDOUT] OptiFineForgeTweaker: acceptOptions
2015-01-30 19:07:24 [INFOS] [STDOUT] OptiFineForgeTweaker: injectIntoClassLoader
2015-01-30 19:07:24 [INFOS] [STDOUT] OptiFine ClassTransformer
2015-01-30 19:07:24 [INFOS] [STDOUT] OptiFine URL: file:/home/nathan/.minecraft/mods/OptiFine_1.7.10_HD_U_A4.jar
2015-01-30 19:07:24 [INFOS] [STDOUT] OptiFine ZIP file: java.util.zip.ZipFile@1dae7f61
2015-01-30 19:07:24 [INFOS] [ForgeModLoader] Calling tweak class cpw.mods.fml.relauncher.CoreModManager$FMLPluginWrapper
2015-01-30 19:07:24 [INFOS] [STDOUT] Loaded 40 rules from AccessTransformer config file fml_at.cfg
2015-01-30 19:07:26 [INFOS] [ForgeModLoader] Found valid fingerprint for Minecraft Forge. Certificate fingerprint e3c3d50c7c986df74c645c0ac54639741c90a557
2015-01-30 19:07:26 [INFOS] [ForgeModLoader] Found valid fingerprint for Minecraft. Certificate fingerprint cd99959656f753dc28d863b46769f7f8fbaefcfc
2015-01-30 19:07:26 [INFOS] [ForgeModLoader] Calling tweak class cpw.mods.fml.relauncher.CoreModManager$FMLPluginWrapper
2015-01-30 19:07:26 [INFOS] [STDOUT] Loaded 110 rules from AccessTransformer config file forge_at.cfg
2015-01-30 19:07:26 [INFOS] [ForgeModLoader] Calling tweak class cpw.mods.fml.common.launcher.FMLDeobfTweaker
2015-01-30 19:07:27 [INFOS] [ForgeModLoader] Calling tweak class shadersmodcore.loading.SMCTweaker
2015-01-30 19:07:27 [INFOS] [STDOUT] OptiFineForgeTweaker: getLaunchArguments
2015-01-30 19:07:27 [INFOS] [ForgeModLoader] Launching wrapped minecraft {net.minecraft.client.main.Main}
2015-01-30 19:07:27 [INFOS] [STDERR] [SMC FNE]transforming atv net.minecraft.client.Minecraft
2015-01-30 19:07:27 [INFOS] [STDERR] [SMC FNE] 58237 (+59)
2015-01-30 19:07:28 [GRAVE] [ForgeModLoader] Unable to launch
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:131)
at net.minecraft.launchwrapper.Launch.main(Launch.java:27)
Caused by: java.lang.NoClassDefFoundError: net/minecraft/client/gui/GuiMainMenu
at net.minecraft.client.main.Main.main(SourceFile:37)
... 6 more
Caused by: java.lang.ClassNotFoundException: net.minecraft.client.gui.GuiMainMenu
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:186)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
... 7 more
Caused by: java.lang.NoClassDefFoundError: bqz
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:178)
... 9 more
Caused by: java.lang.ClassNotFoundException: bqz
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:186)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
... 13 more
Caused by: java.lang.NullPointerException
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:178)
... 15 more