Help. my minecraft doesn't start

It gave me a error after I try to get into the world

---- Minecraft Crash Report ----

// On the bright side, I bought you a teddy bear!

Time: 25/03/13 18:55

Description: Ticking screen

java.lang.ClassCastException: net.minecraft.client.entity.EntityClientPlayerMP cannot be cast to cpw.mods.fml.common.network.Player

at cpw.mods.fml.common.network.NetworkRegistry.handleCustomPacket(NetworkRegistry.java:237)

at cpw.mods.fml.common.network.FMLNetworkHandler.handlePacket250Packet(FMLNetworkHandler.java:83)

at net.minecraft.client.multiplayer.NetClientHandler.func_72501_a(NetClientHandler.java:1571)

at net.minecraft.network.packet.Packet250CustomPayload.func_73279_a(SourceFile:59)

at net.minecraft.network.MemoryConnection.func_74428_b(MemoryConnection.java:89)

at net.minecraft.client.multiplayer.NetClientHandler.func_72551_d(NetClientHandler.java:266)

at net.minecraft.client.gui.GuiDownloadTerrain.func_73876_c(SourceFile:31)

at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1522)

at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:831)

at net.minecraft.client.Minecraft.run(Minecraft.java:756)

at java.lang.Thread.run(Unknown Source)

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

---------------------------------------------------------------------------------------

-- Head --

Stacktrace:

at cpw.mods.fml.common.network.NetworkRegistry.handleCustomPacket(NetworkRegistry.java:237)

at cpw.mods.fml.common.network.FMLNetworkHandler.handlePacket250Packet(FMLNetworkHandler.java:83)

at net.minecraft.client.multiplayer.NetClientHandler.func_72501_a(NetClientHandler.java:1571)

at net.minecraft.network.packet.Packet250CustomPayload.func_73279_a(SourceFile:59)

at net.minecraft.network.MemoryConnection.func_74428_b(MemoryConnection.java:89)

at net.minecraft.client.multiplayer.NetClientHandler.func_72551_d(NetClientHandler.java:266)

at net.minecraft.client.gui.GuiDownloadTerrain.func_73876_c(SourceFile:31)

-- Affected screen --

Details:

Screen name: ~~ERROR~~ NullPointerException: null

-- Affected level --

Details:

Level name: MpServer

All players: 1 total; [EntityClientPlayerMP['carloszune'/215, l='MpServer', x=340,13, y=74,48, z=51,36]]

Chunk stats: MultiplayerChunkCache: 0

Level seed: 0

Level generator: ID 00 - default, ver 1. Features enabled: false

Level generator options:

Level spawn location: World: (236,64,256), Chunk: (at 12,4,0 in 14,16; contains blocks 224,0,256 to 239,255,271), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)

Level time: 1154583 game time, 1172975 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: creative (ID 1). Hardcore: false. Cheats: false

Forced entities: 1 total; [EntityClientPlayerMP['carloszune'/215, l='MpServer', x=340,13, y=74,48, z=51,36]]

Retry entities: 0 total; []

Stacktrace:

at net.minecraft.client.multiplayer.WorldClient.func_72914_a(WorldClient.java:441)

at net.minecraft.client.Minecraft.func_71396_d(Minecraft.java:2405)

at net.minecraft.client.Minecraft.run(Minecraft.java:772)

at java.lang.Thread.run(Unknown Source)

-- System Details --

Details:

Minecraft Version: 1.5.1

Operating System: Windows 8 (x86) version 6.2

Java Version: 1.7.0_09, Oracle Corporation

Java VM Version: Java HotSpot Client VM (mixed mode), Oracle Corporation

Memory: 380529456 bytes (362 MB) / 519110656 bytes (495 MB) up to 1037959168 bytes (989 MB)

JVM Flags: 2 total; -Xms512m -Xmx1024m

AABB Pool Size: 18931 (1060136 bytes; 1 MB) allocated, 2 (112 bytes; 0 MB) used

Suspicious classes: FML and Forge are installed

IntCache: cache: 0, tcache: 2, allocated: 5, tallocated: 59

FML: MCP v7.44 FML v5.1.8.608 Minecraft Forge 7.7.0.608 4 mods loaded, 4 mods active

mcp [Minecraft Coder Pack] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available

FML [Forge Mod Loader] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available

Forge [Minecraft Forge] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available

mod_TooManyItems [mod_TooManyItems] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available

LWJGL: 2.4.2

OpenGL: GeForce 8400GS/PCIe/SSE2 GL version 3.3.0, NVIDIA Corporation

Is Modded: Definitely; Client brand changed to 'forge,fml'

Type: Client (map_client.txt)

Texture Pack: Default

Profiler Position: N/A (disabled)

Vec3 Pool Size: 32 (1792 bytes; 0 MB) allocated, 11 (616 bytes; 0 MB) used