it keeps crashing when i click on multiplayer, but i doesnt crahs when i click on singleplayer. i really want to play, ive been having this issue for weeks now

---- Minecraft Crash Report ----
// I just don't know what went wrong :(

Time: 9/23/15 7:40 PM
Description: Rendering screen

java.lang.IllegalArgumentException: bad Base64 input character at 1049: 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 azk.c(SourceFile:212)
	at azk.a(SourceFile:145)
	at awd.a(SourceFile:25)
	at awi.b(SourceFile:412)
	at awi.a(SourceFile:211)
	at azh.a(SourceFile:291)
	at bfk.a(SourceFile:1039)
	at ave.av(SourceFile:915)
	at ave.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 azk.c(SourceFile:212)
	at azk.a(SourceFile:145)
	at awd.a(SourceFile:25)
	at awi.b(SourceFile:412)
	at awi.a(SourceFile:211)
	at azh.a(SourceFile:291)

-- Screen render details --
Details:
	Screen name: azh
	Mouse location: Scaled: (214, 145). Absolute: (428, 188)
	Screen size: Scaled: (427, 240). Absolute: (854, 480). Scale factor of 2
Stacktrace:
	at bfk.a(SourceFile:1039)
	at ave.av(SourceFile:915)
	at ave.a(SourceFile:325)
	at net.minecraft.client.main.Main.main(SourceFile:124)

-- System Details --
Details:
	Minecraft Version: 1.8.8
	Operating System: Windows XP (x86) version 5.1
	Java Version: 1.8.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
	Memory: 104995128 bytes (100 MB) / 201732096 bytes (192 MB) up to 523501568 bytes (499 MB)
	JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 1.8.8
	LWJGL: 2.9.4
	OpenGL: Intel 945G GL version 1.4.0 - Build 4.14.10.4396, Intel
	GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Not using framebuffer objects because OpenGL 1.4 is not supported, EXT_blend_func_separate is supported, OpenGL 3.0 is not supported, ARB_framebuffer_object is not supported, and EXT_framebuffer_object is not supported.
Shaders are not available because OpenGL 2.1 is not supported, ARB_shader_objects is not supported, ARB_vertex_shader is not supported, and ARB_fragment_shader is not supported.
VBOs are available because ARB_vertex_buffer_object 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)
	CPU: 2x Intel(R) Pentium(R) D CPU 3.40GHz