Forum francais Minecraft. Serveur de jeu FR-Minecraft et astuces pour Minecraft.

Aujourd'hui , j'ai installé un mod nommé "better furnace" qui permet d'avoir plusieurs fours différents. Je l'installe correctement, je lance minecraft , je me connecte et après quelques secondes , un message s'affiche :

Mods loaded: 5
ModLoader 1.2.5
mod_TooManyItems 1.2.5 2012-04-13
mod_VerticalRedstone v5.4
mod_Flatlands 1.2.5
mod_BetterFurnaces null

      Minecraft has crashed!     
      ----------------------     

Minecraft has stopped running because it encountered a problem.

--- BEGIN ERROR REPORT 1898c3ba --------
Generated 21/07/12 18:22

Minecraft: Minecraft 1.2.5
OS: Windows Vista (x86) version 6.0
Java: 1.6.0_33, Sun Microsystems Inc.
VM: Java HotSpot(TM) Client VM (mixed mode), Sun Microsystems Inc.
LWJGL: 2.4.2
OpenGL: ATI Radeon HD 3450 version 2.1.7276 Release, ATI Technologies Inc.

java.lang.IncompatibleClassChangeError: Implementing class
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(Unknown Source)
    at java.lang.ClassLoader.defineClass(Unknown Source)
    at java.security.SecureClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.access$000(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 mod_BetterFurnaces.load(mod_BetterFurnaces.java:57)
    at ModLoader.init(ModLoader.java:891)
    at ModLoader.addAllRenderers(ModLoader.java:189)
    at ahu.<init>(ahu.java:77)
    at ahu.<clinit>(ahu.java:8)
    at net.minecraft.client.Minecraft.a(SourceFile:273)
    at net.minecraft.client.Minecraft.run(SourceFile:657)
    at java.lang.Thread.run(Unknown Source)
--- END ERROR REPORT 85a8e881 ----------

Donc je voudrais savoir comment faire , merci d'avance!
Cordialement, vToXiCs