Minecraft ne marche plus quand je lance une partie solo ou multi

Bonjour, minecraft ne marche plus depuis une semaine dès que je lance une partie solo ou multijoueur il crash j'ai minecraft 8.3 et j'ai la dernière version de java. Voici le crash: Caused by: java.net.ConnectException: Connection timed out: connect
at sun.nio.ch.Net.connect0(Native Method)
at sun.nio.ch.Net.connect(Net.java:457)
at sun.nio.ch.Net.connect(Net.java:449)
at sun.nio.ch.SocketChannelImpl.connect(SocketChannelImpl.java:647)
at java.nio.channels.SocketChannel.open(SocketChannel.java:189)
at sun.nio.ch.PipeImpl$Initializer$LoopbackConnector.run(PipeImpl.java:130)
at sun.nio.ch.PipeImpl$Initializer.run(PipeImpl.java:83)
... 28 more


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Stacktrace:
at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:68)
at io.netty.channel.MultithreadEventLoopGroup.<init>(MultithreadEventLoopGroup.java:49)
at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:61)
at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:52)
at lm$1.a(SourceFile:44)
at lm$1.b(SourceFile:41)
at np.c(SourceFile:10)
at lm.a(SourceFile:121)
at avf.a(SourceFile:1941)
at axw.i(SourceFile:172)
at axw$a.a(SourceFile:224)
at awj.p(SourceFile:315)
at axw.k(SourceFile:82)
at axv.p(SourceFile:390)

-- Affected screen --
Details:
Screen name: ayb
Stacktrace:
at avf.s(SourceFile:1497)
at avf.av(SourceFile:888)
at avf.a(SourceFile:325)
at net.minecraft.client.main.Main.main(SourceFile:124)

-- System Details --
Details:
Minecraft Version: 1.8.3
Operating System: Windows 7 (amd64) version 6.1
CPU: 4x Intel(R) Core(TM) i3-2130 CPU @ 3.40GHz
Java Version: 1.8.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 149468272 bytes (142 MB) / 318398464 bytes (303 MB) up to 1060372480 bytes (1011 MB)
JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
Launched Version: 1.8.3
LWJGL: 2.9.4
OpenGL: ASUS EAH5450 Series GL version 4.0.10055 Compatibility Profile Context, ATI Technologies Inc.
GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

Using VBOs: No
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs: []
Current Language: English (US)
Profiler Position: N/A (disabled)

Et quand je lance une partie multijoueur il écrit ça: java.lang.NullPointerException: group

Merci de votre aide