Y'a aussi ce message :
Minecraft has crashed!
----------------------
Minecraft has stopped running because it encountered a problem; Updating screen events
A full error report has been saved to /Users/jeff/Library/Application Support/minecraft/crash-reports/crash-2013-03-23_1
6.18.27-client.txt
- Please include a copy of that file (Not this screen!) if you report this crash to anyone; without it, they will not be able to help fix the crash 
--- BEGIN ERROR REPORT d91aeac3 --------
Full report at:
/Users/jeff/Library/Application Support/minecraft/crash-reports/crash-2013-03-23_1
6.18.27-client.txt
Please show that file to Mojang, NOT just this screen!
Generated 23/03/13 16:18
-- Head --
Stacktrace:
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.
java:631)
at java.lang.ClassLoader.defineClass(ClassLoader.java
:615)
at java.security.SecureClassLoader.defineClass(Secure
ClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader
.java:283)
at java.net.URLClassLoader.access$000(URLClassLoader.
java:58)
at java.net.URLClassLoader$1.run(URLClassLoader.java:
197)
at java.security.AccessController.doPrivileged(Native
Method)
at java.net.URLClassLoader.findClass(URLClassLoader.j
ava:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:3
06)
at java.lang.ClassLoader.loadClass(ClassLoader.java:2
47)
at net.minecraft.server.MinecraftServer.<init>(Source
File:96)
at bjh.<init>(SourceFile:35)
at net.minecraft.client.Minecraft.a(SourceFile:1378)
at axu.e(SourceFile:166)
at axu.a(SourceFile:131)
at axr.a(SourceFile:72)
at axr.d(SourceFile:127)
at axr.m(SourceFile:111)
-- Affected screen --
Details:
Screen name: bkg
Stacktrace:
at net.minecraft.client.Minecraft.l(SourceFile:1078)
at net.minecraft.client.Minecraft.K(SourceFile:574)
at net.minecraft.client.Minecraft.run(SourceFile:526)
at java.lang.Thread.run(Thread.java:680)
-- System Details --
Details:
Minecraft Version: 1.5.1
Operating System: Mac OS X (x86_64) version 10.7.5
Java Version: 1.6.0_37, Apple Inc.
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
Memory: 547873856 bytes (522 MB) / 581435392 bytes (554 MB) up to 1065025536 bytes (1015 MB)
JVM Flags: 3 total; -Xbootclasspath/a:/System/Library/PrivateFramework
s/JavaApplicationLauncher.framework/Resources/Laun
cherSupport.jar
-Xms512M -Xmx1024M
AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
Suspicious classes: No suspicious classes found.
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
LWJGL: 2.4.2
OpenGL: ATI Radeon HD 6970M OpenGL Engine GL version 2.1 ATI-7.32.12, ATI Technologies Inc.
Is Modded: Very likely; Jar signature invalidated
Type: Client (map_client.txt)
Texture Pack: Default
Profiler Position: N/A (disabled)
Vec3 Pool Size: ~~ERROR~~ NullPointerException: null
java.lang.IncompatibleClassChangeError: Implementing class
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.
java:631)
at java.lang.ClassLoader.defineClass(ClassLoader.java
:615)
at java.security.SecureClassLoader.defineClass(Secure
ClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader
.java:283)
at java.net.URLClassLoader.access$000(URLClassLoader.
java:58)
at java.net.URLClassLoader$1.run(URLClassLoader.java:
197)
at java.security.AccessController.doPrivileged(Native
Method)
at java.net.URLClassLoader.findClass(URLClassLoader.j
ava:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:3
06)
at java.lang.ClassLoader.loadClass(ClassLoader.java:2
47)
at net.minecraft.server.MinecraftServer.<init>(Source
File:96)
at bjh.<init>(SourceFile:35)
at net.minecraft.client.Minecraft.a(SourceFile:1378)
at axu.e(SourceFile:166)
at axu.a(SourceFile:131)
at axr.a(SourceFile:72)
at axr.d(SourceFile:127)
at axr.m(SourceFile:111)
at net.minecraft.client.Minecraft.l(SourceFile:1078)
at net.minecraft.client.Minecraft.K(SourceFile:574)
at net.minecraft.client.Minecraft.run(SourceFile:526)
at java.lang.Thread.run(Thread.java:680)
--- END ERROR REPORT ec94e9eb ----------
