i can't write anything on minecraft :/ and when i do this happens:

---- Minecraft Crash Report ----
// This doesn't make any sense!

Time: 7/9/13 9:37 AM
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: 12 total; [bdf['Markus4445'/34101, l='MpServer', x=1.11, y=9.61, z=19.20], bev['Grapefruit_UY'/26957, l='MpServer', x=0.00, y=6.00, z=0.00], bev['carterlim'/2214, l='MpServer', x=0.00, y=6.00, z=0.00], bev['kong109'/33653, l='MpServer', x=0.00, y=6.00, z=0.00], bev['freeboy32'/32849, l='MpServer', x=2.22, y=5.00, z=9.34], bev['RecklessElias'/89, l='MpServer', x=0.00, y=6.00, z=0.00], bev['zappa1911'/20992, l='MpServer', x=0.00, y=6.02, z=0.00], bev['jessedean1'/24536, l='MpServer', x=0.00, y=6.02, z=0.00], bev['A_G_Blue'/34108, l='MpServer', x=-3.37, y=6.00, z=0.04], bev['BayLeafly'/34109, l='MpServer', x=-7.00, y=4.50, z=14.94], bev['LeandroSchenker'/34110, l='MpServer', x=0.00, y=6.00, z=0.00], bev['Camsepic2'/34111, l='MpServer', x=2.13, y=6.00, z=-0.22]]
Chunk stats: MultiplayerChunkCache: 441
Level seed: 0
Level generator: ID 01 - flat, ver 0. Features enabled: false
Level generator options:
Level spawn location: World: (5,5,3), Chunk: (at 5,0,3 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 129856406 game time, 183606008 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: 34 total; [bdf['Markus4445'/34101, l='MpServer', x=1.11, y=9.61, z=19.20], bev['Grapefruit_UY'/26957, l='MpServer', x=0.00, y=6.00, z=0.00], bev['zappa1911'/20992, l='MpServer', x=0.00, y=6.02, z=0.00], bev['carterlim'/2214, l='MpServer', x=0.00, y=6.00, z=0.00], bev['kong109'/33653, l='MpServer', x=0.00, y=6.00, z=0.00], bev['freeboy32'/32849, l='MpServer', x=2.22, y=5.00, z=9.34], bev['LeandroSchenker'/34110, l='MpServer', x=0.00, y=6.00, z=0.00], bev['RecklessElias'/89, l='MpServer', x=0.00, y=6.00, z=0.00], bev['spiffywaffleman'/34093, l='MpServer', x=10.10, y=4.00, z=18.02], bev['zappa1911'/20992, l='MpServer', x=0.00, y=6.02, z=0.00], bev['jessedean1'/24536, l='MpServer', x=0.00, y=6.02, z=0.00], bev['Camsepic2'/34111, l='MpServer', x=2.13, y=6.00, z=-0.22], bev['kevin0921'/34100, l='MpServer', x=0.41, y=3.84, z=20.09], bev['xj3ffx2'/34081, l='MpServer', x=10.31, y=4.00, z=-16.50], bev['Rubiks_dude'/34092, l='MpServer', x=-9.75, y=5.00, z=-1.78], bev['kong109'/33653, l='MpServer', x=0.00, y=6.00, z=0.00], bev['creeperfauto'/34096, l='MpServer', x=7.00, y=5.00, z=7.22], bev['Grapefruit_UY'/26957, l='MpServer', x=0.00, y=6.00, z=0.00], bev['Seanyboy712'/34104, l='MpServer', x=3.00, y=6.00, z=4.72], bev['RecklessElias'/89, l='MpServer', x=0.00, y=6.00, z=0.00], bev['freeboy32'/32849, l='MpServer', x=2.22, y=5.00, z=9.34], bev['A_G_Blue'/34108, l='MpServer', x=-3.37, y=6.00, z=0.04], bev['jessedean1'/24536, l='MpServer', x=0.00, y=6.02, z=0.00], bev['LuclidHD'/34103, l='MpServer', x=-2.63, y=5.00, z=10.22], bev['flechman'/34107, l='MpServer', x=-10.22, y=4.00, z=17.88], bev['BayLeafly'/34109, l='MpServer', x=-7.00, y=4.50, z=14.94], bev['BayLeafly'/34109, l='MpServer', x=-7.00, y=4.50, z=14.94], bev['A_G_Blue'/34108, l='MpServer', x=-3.37, y=6.00, z=0.04], bev['Camsepic2'/34111, l='MpServer', x=2.13, y=6.00, z=-0.22], bev['LeandroSchenker'/34110, l='MpServer', x=0.00, y=6.00, z=0.00], bev['XxBabeSwagxX'/34106, l='MpServer', x=18.44, y=4.00, z=8.00], bev['Winarve'/34105, l='MpServer', x=-8.63, y=4.00, z=16.94], bev['carterlim'/2214, l='MpServer', x=0.00, y=6.00, z=0.00], bev['Yooda99'/34102, l='MpServer', x=4.85, y=5.48, z=14.73]]
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: 12 total; [bdf['Markus4445'/34101, l='MpServer', x=1.11, y=9.61, z=19.20], bev['Grapefruit_UY'/26957, l='MpServer', x=0.00, y=6.00, z=0.00], bev['carterlim'/2214, l='MpServer', x=0.00, y=6.00, z=0.00], bev['kong109'/33653, l='MpServer', x=0.00, y=6.00, z=0.00], bev['freeboy32'/32849, l='MpServer', x=2.22, y=5.00, z=9.34], bev['RecklessElias'/89, l='MpServer', x=0.00, y=6.00, z=0.00], bev['zappa1911'/20992, l='MpServer', x=0.00, y=6.02, z=0.00], bev['jessedean1'/24536, l='MpServer', x=0.00, y=6.02, z=0.00], bev['A_G_Blue'/34108, l='MpServer', x=-3.37, y=6.00, z=0.04], bev['BayLeafly'/34109, l='MpServer', x=-7.00, y=4.50, z=14.94], bev['LeandroSchenker'/34110, l='MpServer', x=0.00, y=6.00, z=0.00], bev['Camsepic2'/34111, l='MpServer', x=2.13, y=6.00, z=-0.22]]
Chunk stats: MultiplayerChunkCache: 441
Level seed: 0
Level generator: ID 01 - flat, ver 0. Features enabled: false
Level generator options:
Level spawn location: World: (5,5,3), Chunk: (at 5,0,3 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 129856406 game time, 183606008 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: 34 total; [bdf['Markus4445'/34101, l='MpServer', x=1.11, y=9.61, z=19.20], bev['Grapefruit_UY'/26957, l='MpServer', x=0.00, y=6.00, z=0.00], bev['zappa1911'/20992, l='MpServer', x=0.00, y=6.02, z=0.00], bev['carterlim'/2214, l='MpServer', x=0.00, y=6.00, z=0.00], bev['kong109'/33653, l='MpServer', x=0.00, y=6.00, z=0.00], bev['freeboy32'/32849, l='MpServer', x=2.22, y=5.00, z=9.34], bev['LeandroSchenker'/34110, l='MpServer', x=0.00, y=6.00, z=0.00], bev['RecklessElias'/89, l='MpServer', x=0.00, y=6.00, z=0.00], bev['spiffywaffleman'/34093, l='MpServer', x=10.10, y=4.00, z=18.02], bev['zappa1911'/20992, l='MpServer', x=0.00, y=6.02, z=0.00], bev['jessedean1'/24536, l='MpServer', x=0.00, y=6.02, z=0.00], bev['Camsepic2'/34111, l='MpServer', x=2.13, y=6.00, z=-0.22], bev['kevin0921'/34100, l='MpServer', x=0.41, y=3.84, z=20.09], bev['xj3ffx2'/34081, l='MpServer', x=10.31, y=4.00, z=-16.50], bev['Rubiks_dude'/34092, l='MpServer', x=-9.75, y=5.00, z=-1.78], bev['kong109'/33653, l='MpServer', x=0.00, y=6.00, z=0.00], bev['creeperfauto'/34096, l='MpServer', x=7.00, y=5.00, z=7.22], bev['Grapefruit_UY'/26957, l='MpServer', x=0.00, y=6.00, z=0.00], bev['Seanyboy712'/34104, l='MpServer', x=3.00, y=6.00, z=4.72], bev['RecklessElias'/89, l='MpServer', x=0.00, y=6.00, z=0.00], bev['freeboy32'/32849, l='MpServer', x=2.22, y=5.00, z=9.34], bev['A_G_Blue'/34108, l='MpServer', x=-3.37, y=6.00, z=0.04], bev['jessedean1'/24536, l='MpServer', x=0.00, y=6.02, z=0.00], bev['LuclidHD'/34103, l='MpServer', x=-2.63, y=5.00, z=10.22], bev['flechman'/34107, l='MpServer', x=-10.22, y=4.00, z=17.88], bev['BayLeafly'/34109, l='MpServer', x=-7.00, y=4.50, z=14.94], bev['BayLeafly'/34109, l='MpServer', x=-7.00, y=4.50, z=14.94], bev['A_G_Blue'/34108, l='MpServer', x=-3.37, y=6.00, z=0.04], bev['Camsepic2'/34111, l='MpServer', x=2.13, y=6.00, z=-0.22], bev['LeandroSchenker'/34110, l='MpServer', x=0.00, y=6.00, z=0.00], bev['XxBabeSwagxX'/34106, l='MpServer', x=18.44, y=4.00, z=8.00], bev['Winarve'/34105, l='MpServer', x=-8.63, y=4.00, z=16.94], bev['carterlim'/2214, l='MpServer', x=0.00, y=6.00, z=0.00], bev['Yooda99'/34102, l='MpServer', x=4.85, y=5.48, z=14.73]]
Retry entities: 0 total; []
Server brand: craftbukkit
Server type: Non-integrated multiplayer server

– System Details –
Details:
Minecraft Version: 1.6.2
Operating System: Mac OS X (x86_64) version 10.8.4
Java Version: 1.6.0_51, Apple Inc.
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
Memory: 53214208 bytes (50 MB) / 124456960 bytes (118 MB) up to 2130051072 bytes (2031 MB)
JVM Flags: 1 total; -Xmx2G
AABB Pool Size: 202 (11312 bytes; 0 MB) allocated, 46 (2576 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: AMD Radeon HD 6970M OpenGL Engine GL version 2.1 ATI-1.8.18, 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: Canadian English (CA)
Profiler Position: N/A (disabled)
Vec3 Pool Size: 50 (2800 bytes; 0 MB) allocated, 24 (1344 bytes; 0 MB) used