Constant crashing

Put the summary of the bug you're having here

---- Minecraft Crash Report ----
// Don't be sad, have a hug! <3

Time: 11/9/13 10:30 PM
Description: Unexpected error

java.lang.ClassCastException: wq cannot be cast to xl
at biv.a(SourceFile:469)
at ft.a(SourceFile:44)
at ft.a(SourceFile:10)
at ef.a(SourceFile:164)
at biy.e(SourceFile:212)
at azd.o(SourceFile:1281)
at azd.ad(SourceFile:753)
at azd.e(SourceFile:704)
at net.minecraft.client.main.Main.main(SourceFile:103)

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

– Head –
Stacktrace:
at biv.a(SourceFile:469)
at ft.a(SourceFile:44)
at ft.a(SourceFile:10)
at ef.a(SourceFile:164)
at biy.e(SourceFile:212)

– Affected level –
Details:
Level name: MpServer
All players: 1 total; [bje['dmulloy2'/56510, l='MpServer', x=1.50, y=70.62, z=0.50]]
Chunk stats: MultiplayerChunkCache: 70, 70
Level seed: 0
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: World: (-299,69,759), Chunk: (at 5,4,7 in -19,47; contains blocks -304,0,752 to -289,255,767), Region: (-1,1; contains chunks -32,32 to -1,63, blocks -512,0,512 to -1,255,1023)
Level time: 615760946 game time, 729339750 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: 11 total; [va['Pig'/56511, l='MpServer', x=0.53, y=64.00, z=24.53], bje['dmulloy2'/56510, l='MpServer', x=1.50, y=70.62, z=0.50], wq['carfan1188'/-2147483643, l='MpServer', x=-242.64, y=62.80, z=354.06], va['Pig'/56512, l='MpServer', x=-1.50, y=76.00, z=20.47], us['Chicken'/56513, l='MpServer', x=24.47, y=69.00, z=-5.38], vb['Sheep'/56514, l='MpServer', x=17.91, y=75.00, z=30.72], ut['Cow'/56515, l='MpServer', x=28.16, y=80.00, z=29.69], us['Chicken'/56516, l='MpServer', x=16.56, y=56.00, z=-27.53], uq['Bat'/56517, l='MpServer', x=-9.59, y=37.11, z=-34.25], ut['Cow'/56518, l='MpServer', x=19.16, y=76.00, z=48.56], ut['Cow'/56519, l='MpServer', x=-24.69, y=72.00, z=-47.50]]
Retry entities: 0 total; []
Server brand: craftbukkit
Server type: Non-integrated multiplayer server
Stacktrace:
at biz.a(SourceFile:284)
at azd.b(SourceFile:1951)
at azd.e(SourceFile:718)
at net.minecraft.client.main.Main.main(SourceFile:103)

– System Details –
Details:
Minecraft Version: 1.7.2
Operating System: Windows 8 (amd64) version 6.2
Java Version: 1.7.0_40, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 171662952 bytes (163 MB) / 377487360 bytes (360 MB) up to 954728448 bytes (910 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
AABB Pool Size: 17507 (980392 bytes; 0 MB) allocated, 2 (112 bytes; 0 MB) used
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 1.7.2
LWJGL: 2.9.0
OpenGL: Intel(R) HD Graphics 4000 GL version 4.0.0 - Build 9.17.10.2843, Intel
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)
Vec3 Pool Size: 424 (23744 bytes; 0 MB) allocated, 23 (1288 bytes; 0 MB) used
Anisotropic Filtering: Off (1)

What I expected to happen was...:
Describe what you thought should happen here

Not to crash

What actually happened was...:
Describe what happened here

Client crashes

Steps to Reproduce:
1. Join my server
2. Walk a few steps
3. Crash