Minecraft: Ayuda crash Pixelmon

Entro en un servidor de Pixelmon y automáticamente me crashea y la verdad es que ni me imagino por qué.
[spoiler]---- Minecraft Crash Report ----
// I'm sorry, Dave.

Time: 5/05/14 20:37
Description: Exception in world tick

java.lang.NullPointerException
	at net.minecraft.client.multiplayer.GuiConnecting.forceTermination(GuiConnecting.java:161)
	at cpw.mods.fml.client.FMLClientHandler.disconnectIDMismatch(FMLClientHandler.java:598)
	at cpw.mods.fml.common.FMLCommonHandler.disconnectIDMismatch(FMLCommonHandler.java:463)
	at cpw.mods.fml.common.network.ModIdMapPacket.execute(ModIdMapPacket.java:101)
	at cpw.mods.fml.common.network.FMLNetworkHandler.handleFMLPacket(FMLNetworkHandler.java:116)
	at cpw.mods.fml.common.network.FMLNetworkHandler.handlePacket250Packet(FMLNetworkHandler.java:81)
	at net.minecraft.client.multiplayer.NetClientHandler.func_72501_a(NetClientHandler.java:1651)
	at net.minecraft.network.packet.Packet250CustomPayload.func_73279_a(SourceFile:61)
	at net.minecraft.network.TcpConnection.func_74428_b(TcpConnection.java:462)
	at net.minecraft.client.multiplayer.NetClientHandler.func_72551_d(NetClientHandler.java:281)
	at net.minecraft.client.multiplayer.WorldClient.func_72835_b(WorldClient.java:99)
	at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1930)
	at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:910)
	at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:838)
	at net.minecraft.client.main.Main.main(SourceFile:101)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at net.minecraft.launchwrapper.Launch.launch(Launch.java:131)
	at net.minecraft.launchwrapper.Launch.main(Launch.java:27)


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

-- Head --
Stacktrace:
	at net.minecraft.client.multiplayer.GuiConnecting.forceTermination(GuiConnecting.java:161)
	at cpw.mods.fml.client.FMLClientHandler.disconnectIDMismatch(FMLClientHandler.java:598)
	at cpw.mods.fml.common.FMLCommonHandler.disconnectIDMismatch(FMLCommonHandler.java:463)
	at cpw.mods.fml.common.network.ModIdMapPacket.execute(ModIdMapPacket.java:101)
	at cpw.mods.fml.common.network.FMLNetworkHandler.handleFMLPacket(FMLNetworkHandler.java:116)
	at cpw.mods.fml.common.network.FMLNetworkHandler.handlePacket250Packet(FMLNetworkHandler.java:81)
	at net.minecraft.client.multiplayer.NetClientHandler.func_72501_a(NetClientHandler.java:1651)
	at net.minecraft.network.packet.Packet250CustomPayload.func_73279_a(SourceFile:61)
	at net.minecraft.network.TcpConnection.func_74428_b(TcpConnection.java:462)
	at net.minecraft.client.multiplayer.NetClientHandler.func_72551_d(NetClientHandler.java:281)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [EntityClientPlayerMP['jrcl39'/3313447, l='MpServer', x=1426,36, y=197,31, z=-234,53]]
	Chunk stats: MultiplayerChunkCache: 441
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: World: (1448,201,-230), Chunk: (at 8,12,10 in 90,-15; contains blocks 1440,0,-240 to 1455,255,-225), Region: (2,-1; contains chunks 64,-32 to 95,-1, blocks 1024,0,-512 to 1535,255,-1)
	Level time: 27742209 game time, 27784123 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: true), thunder time: 0 (now: false)
	Level game mode: Game mode: adventure (ID 2). Hardcore: false. Cheats: false
	Forced entities: 3 total; [EntityClientPlayerMP['jrcl39'/3313447, l='MpServer', x=1426,36, y=197,31, z=-234,53], EntityOtherPlayerMP['david10pitu'/3313517, l='MpServer', x=1426,53, y=195,13, z=-233,41], EntityOtherPlayerMP['MrSokka'/3313558, l='MpServer', x=1425,50, y=195,13, z=-234,75]]
	Retry entities: 0 total; []
	Server brand: craftbukkit
	Server type: Non-integrated multiplayer server
Stacktrace:
	at net.minecraft.client.multiplayer.WorldClient.func_72914_a(WorldClient.java:440)
	at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1943)
	at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:910)
	at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:838)
	at net.minecraft.client.main.Main.main(SourceFile:101)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at net.minecraft.launchwrapper.Launch.launch(Launch.java:131)
	at net.minecraft.launchwrapper.Launch.main(Launch.java:27)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [EntityClientPlayerMP['jrcl39'/3313447, l='MpServer', x=1426,36, y=197,31, z=-234,53]]
	Chunk stats: MultiplayerChunkCache: 441
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: World: (1448,201,-230), Chunk: (at 8,12,10 in 90,-15; contains blocks 1440,0,-240 to 1455,255,-225), Region: (2,-1; contains chunks 64,-32 to 95,-1, blocks 1024,0,-512 to 1535,255,-1)
	Level time: 27742209 game time, 27784123 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: true), thunder time: 0 (now: false)
	Level game mode: Game mode: adventure (ID 2). Hardcore: false. Cheats: false
	Forced entities: 3 total; [EntityClientPlayerMP['jrcl39'/3313447, l='MpServer', x=1426,36, y=197,31, z=-234,53], EntityOtherPlayerMP['david10pitu'/3313517, l='MpServer', x=1426,53, y=195,13, z=-233,41], EntityOtherPlayerMP['MrSokka'/3313558, l='MpServer', x=1425,50, y=195,13, z=-234,75]]
	Retry entities: 0 total; []
	Server brand: craftbukkit
	Server type: Non-integrated multiplayer server

-- System Details --
Details:
	Minecraft Version: 1.6.4
	Operating System: Windows Vista (x86) version 6.0
	Java Version: 1.7.0_55, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 96025440 bytes (91 MB) / 223657984 bytes (213 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 13635 (763560 bytes; 0 MB) allocated, 13 (728 bytes; 0 MB) used
	Suspicious classes: FML and Forge are installed
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	FML: MCP v8.11 FML v6.4.49.965 Minecraft Forge 9.11.1.965 4 mods loaded, 4 mods active
	mcp{8.09} [Minecraft Coder Pack] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
	FML{6.4.49.965} [Forge Mod Loader] (minecraftforge-9.11.1.965.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
	Forge{9.11.1.965} [Minecraft Forge] (minecraftforge-9.11.1.965.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
	pixelmon{3.0.4} [Pixelmon] (Pixelmon 3.0.4.zip) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
	Launched Version: 1.6.4-Forge9.11.1.965
	LWJGL: 2.9.0
	OpenGL: GeForce 8400M GS/PCI/SSE2/3DNOW! GL version 3.1 NVIDIA 187.66, NVIDIA Corporation
	Is Modded: Definitely; Client brand changed to 'fml,forge'
	Type: Client (map_client.txt)
	Resource Pack: Default
	Current Language: Español (España)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 130 (7280 bytes; 0 MB) allocated, 25 (1400 bytes; 0 MB) used[/spoiler]