When trying to open in multiplayer it crashes and I get a crash report

Put the summary of the bug you're having here

When I click on multiplayer Minecraft crashes and goes straight to the Crash report screen
This happens everytime I attempt to access multiplayer
I have clicked on report to Mojang and nothing has happened to improve this

Details as follows:7

Minecraft Crash Report ----
// Hey, that tickles! Hehehe!

Time: 03/04/15 17:24
Description: Rendering screen

java.lang.IllegalArgumentException: bad Base64 input character at 3129: 63 (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 bzr.c(SourceFile:212)
at bzr.a(SourceFile:145)
at bus.a(SourceFile:25)
at bvi.b(SourceFile:409)
at bvi.a(SourceFile:217)
at bzo.a(SourceFile:291)
at cjh.b(SourceFile:1026)
at bss.at(SourceFile:906)
at bss.a(SourceFile:317)
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 bzr.c(SourceFile:212)
at bzr.a(SourceFile:145)
at bus.a(SourceFile:25)
at bvi.b(SourceFile:409)
at bvi.a(SourceFile:217)
at bzo.a(SourceFile:291)

– Screen render details –
Details:
Screen name: bzo
Mouse location: Scaled: (217, 147). Absolute: (435, 184)
Screen size: Scaled: (427, 240). Absolute: (854, 480). Scale factor of 2
Stacktrace:
at cjh.b(SourceFile:1026)
at bss.at(SourceFile:906)
at bss.a(SourceFile:317)
at net.minecraft.client.main.Main.main(SourceFile:124)

– System Details –
Details:
Minecraft Version: 1.8.1
Operating System: Windows 8.1 (amd64) version 6.3
Java Version: 1.8.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 74023088 bytes (70 MB) / 240209920 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: 1.8.1
LWJGL: 2.9.1
OpenGL: Intel(R) HD Graphics GL version 4.0.0 - Build 10.18.10.3282, 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 (UK)
Profiler Position: N/A (disabled)