When I click on the button " Multiplayer ", minecraft crash

I can open minecraft, play in Singleplayer, use options, ... but when I click on the button " Multiplayer " after 2-3 seconds, my game just crash. I paste the crash reprot just below.

---- Minecraft Crash Report ----
// Don't do that.

Time: 26/02/15 01:26
Description: Rendering screen

java.lang.IllegalArgumentException: bad Base64 input character at 4022: 0 (decimal)
	at io.netty.handler.codec.base64.Base64.decode(Base64.java:247)
	at io.netty.handler.codec.base64.Base64.decode(Base64.java:197)
	at io.netty.handler.codec.base64.Base64.decode(Base64.java:188)
	at azl.c(SourceFile:212)
	at azl.a(SourceFile:145)
	at awe.a(SourceFile:25)
	at awj.b(SourceFile:412)
	at awj.a(SourceFile:211)
	at azi.a(SourceFile:291)
	at bfl.a(SourceFile:1039)
	at avf.av(SourceFile:914)
	at avf.a(SourceFile:325)
	at net.minecraft.client.main.Main.main(SourceFile:124)


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

-- Head --
Stacktrace:
	at io.netty.handler.codec.base64.Base64.decode(Base64.java:247)
	at io.netty.handler.codec.base64.Base64.decode(Base64.java:197)
	at io.netty.handler.codec.base64.Base64.decode(Base64.java:188)
	at azl.c(SourceFile:212)
	at azl.a(SourceFile:145)
	at awe.a(SourceFile:25)
	at awj.b(SourceFile:412)
	at awj.a(SourceFile:211)
	at azi.a(SourceFile:291)

-- Screen render details --
Details:
	Screen name: azi
	Mouse location: Scaled: (398, 172). Absolute: (796, 360)
	Screen size: Scaled: (683, 353). Absolute: (1366, 705). Scale factor of 2
Stacktrace:
	at bfl.a(SourceFile:1039)
	at avf.av(SourceFile:914)
	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 8.1 (amd64) version 6.3
	CPU: 1x Intel(R) Celeron(R) CPU G440 @ 1.60GHz
	Java Version: 1.8.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 77231336 bytes (73 MB) / 240521216 bytes (229 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: 0, tallocated: 0
	Launched Version: 1.8.3
	LWJGL: 2.9.4
	OpenGL: Intel(R) HD Graphics GL version 3.1.0 - Build 9.17.10.3347, Intel
	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)