Chat crashes when used

Launch Minecraft
Join Server
Try to chat
Crash 😞

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

Time: 10-07-2013 19:56
Description: Deserializing Message

java.lang.ClassCastException: com.google.gson.JsonPrimitive cannot be cast to com.google.gson.JsonObject
	at cw.a(SourceFile:14)
	at cw.deserialize(SourceFile:10)
	at com.google.gson.TreeTypeAdapter.read(TreeTypeAdapter.java:58)
	at com.google.gson.Gson.fromJson(Gson.java:795)
	at com.google.gson.Gson.fromJson(Gson.java:761)
	at com.google.gson.Gson.fromJson(Gson.java:710)
	at com.google.gson.Gson.fromJson(Gson.java:682)
	at cu.c(SourceFile:220)
	at bct.a(SourceFile:522)
	at dl.a(SourceFile:49)
	at cn.b(SourceFile:354)
	at bct.e(SourceFile:98)
	at bda.b(SourceFile:60)
	at ats.k(SourceFile:1386)
	at ats.S(SourceFile:663)
	at ats.d(SourceFile:619)
	at net.minecraft.client.main.Main.main(SourceFile:101)


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

-- Head --
Stacktrace:
	at cw.a(SourceFile:14)
	at cw.deserialize(SourceFile:10)
	at com.google.gson.TreeTypeAdapter.read(TreeTypeAdapter.java:58)
	at com.google.gson.Gson.fromJson(Gson.java:795)
	at com.google.gson.Gson.fromJson(Gson.java:761)
	at com.google.gson.Gson.fromJson(Gson.java:710)
	at com.google.gson.Gson.fromJson(Gson.java:682)

-- Serialized Message --
Details:
	JSON string: Cannot send chat message.
Stacktrace:
	at cu.c(SourceFile:220)
	at bct.a(SourceFile:522)
	at dl.a(SourceFile:49)
	at cn.b(SourceFile:354)
	at bct.e(SourceFile:98)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bdf['TugaKid'/234, l='MpServer', x=10,37, y=73,62, z=5,46]]
	Chunk stats: MultiplayerChunkCache: 441
	Level seed: 0
	Level generator: ID 00 - default, ver 1. Features enabled: false
	Level generator options: 
	Level spawn location: World: (-10,82,10), Chunk: (at 6,5,10 in -1,0; contains blocks -16,0,0 to -1,255,15), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
	Level time: 10939565 game time, 11043865 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
	Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
	Forced entities: 1 total; [bdf['TugaKid'/234, l='MpServer', x=10,37, y=73,62, z=5,46]]
	Retry entities: 0 total; []
	Server brand: craftbukkit
	Server type: Non-integrated multiplayer server
Stacktrace:
	at bda.a(SourceFile:284)
	at ats.k(SourceFile:1393)
	at ats.S(SourceFile:663)
	at ats.d(SourceFile:619)
	at net.minecraft.client.main.Main.main(SourceFile:101)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bdf['TugaKid'/234, l='MpServer', x=10,37, y=73,62, z=5,46]]
	Chunk stats: MultiplayerChunkCache: 441
	Level seed: 0
	Level generator: ID 00 - default, ver 1. Features enabled: false
	Level generator options: 
	Level spawn location: World: (-10,82,10), Chunk: (at 6,5,10 in -1,0; contains blocks -16,0,0 to -1,255,15), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
	Level time: 10939565 game time, 11043865 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
	Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
	Forced entities: 1 total; [bdf['TugaKid'/234, l='MpServer', x=10,37, y=73,62, z=5,46]]
	Retry entities: 0 total; []
	Server brand: craftbukkit
	Server type: Non-integrated multiplayer server

-- System Details --
Details:
	Minecraft Version: 1.6.2
	Operating System: Windows 8 (x86) version 6.2
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 83136200 bytes (79 MB) / 146853888 bytes (140 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 1 total; -Xmx512M
	AABB Pool Size: 16 (896 bytes; 0 MB) allocated, 14 (784 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 1.6.2
	LWJGL: 2.9.0
	OpenGL: ATI Radeon HD 4730 Series GL version 3.3.11653 Compatibility Profile Context, ATI Technologies Inc.
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Pack: Default
	Current Language: Português (Portugal)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 39 (2184 bytes; 0 MB) allocated, 13 (728 bytes; 0 MB) used