Voila,j'ai formater mon PC et minecraft ne se lance pas après le luancher qui bloque.
J'ai java 8 64 bits.

Le code d'erreur:
Set run directory to C:\Program Files (x86)\Minecraft
Native Launcher Version: 307
Operating System: Windows 7 Professional
Application Hash: 40a55daa6845b0e1e797461386a218193b14e7d6
Application Data directory: C:\Users\Cyclope\AppData\Roaming
Executable Path: MinecraftLauncher.exe
App Directory dir: C:\Program Files (x86)\Minecraft
Start dir: C:/Program Files (x86)/Minecraft
Launcher dir: C:/Program Files (x86)/Minecraft/game
TmpDir dir: C:/Program Files (x86)/Minecraft/game
Java Launcher hash: ccb4a2df12fa3bd8c4d27ece46f692d12f91a01b
Java Version: 1.8.0_25
x64: 1
LauncherConfiguration from: https://launchermeta.mojang.com/mc/launcher.json
Downloaded config
Native launcher is current
Native launcher is current
Java launcher is current: ccb4a2df12fa3bd8c4d27ece46f692d12f91a01b(ccb4a2df12fa3bd8c4d27ece46f692d12f91a01b)
Check to see if we can run the launcher
Native launcher is current
runJavaLauncher
Started application ./runtime/jre-x64/1.8.0_25/bin/java.exe -cp "C:/Program Files (x86)/Minecraft/game/launcher.jar" net.minecraft.launcher.Main --nativeLauncherVersion 307
Application still running, assuming all's fine.

Il me dise aussi [20:21:38 WARN]: Had local file but it was the wrong size... had 55128 but expected 70341

Et aussi [20:21:47 WARN]: Couldn't download http://resources.download.minecraft.net/9b/9b2a01e0d0456b8fbe33557fbc19d4fe342f94d6 for job 'Resources'
java.net.SocketTimeoutException: Read timed out

deja ton .minecraft, il faut le metttre dans C:\Users\Cyclope\AppData\Roaming\.minecraft
et pas dans C:\Program Files (x86)\.minecraft

Merci,Je vais tester!

Mon .minecraft est deja la bas