Crash-reports

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

Time: 2/2/13 9:57 PM
Description: Exception in server tick loop

java.lang.IllegalArgumentException: Failed to register dimension for id 0, One is already registered
	at net.minecraftforge.common.DimensionManager.registerDimension(DimensionManager.java:66)
	at xcompwiz.mystcraft.MystcraftEventHandler.registerDimensions(MystcraftEventHandler.java:50)
	at xcompwiz.mystcraft.MystcraftEventHandler.handleWorldLoadEvent(MystcraftEventHandler.java:37)
	at net.minecraftforge.event.ASMEventHandler_58_MystcraftEventHandler_handleWorldLoadEvent_Load.invoke(.dynamic)
	at net.minecraftforge.event.ASMEventHandler.invoke(ASMEventHandler.java:35)
	at net.minecraftforge.event.EventBus.post(EventBus.java:103)
	at net.minecraft.server.MinecraftServer.a(MinecraftServer.java:278)
	at hg.c(DedicatedServer.java:153)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:454)
	at fp.run(SourceFile:818)

Relevant Details:
- Minecraft Version: 1.4.2
- Operating System: Linux (amd64) version 3.2.0-36-generic
- Java Version: 1.7.0_09, Oracle Corporation
- Java VM Version: OpenJDK 64-Bit Server VM (mixed mode), Oracle Corporation
- Memory: 302363408 bytes (288 MB) / 751632384 bytes (716 MB) up to 4241293312 bytes (4044 MB)
- JVM Flags: 9 total; -Xmx4096M -Xms768M -Xmn512M -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+CMSIncrementalPacing -XX:ParallelGCThreads=2 -XX:+AggressiveOpts -Xincgc
- AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
- FML: ~ERROR~ NullPointerException: null
- Is Modded: Definitely; 'forge,fml'
- Profiler Position: N/A (disabled)
- Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
- Player Count: 0 / 50; []
- World world Entities: 0 total; []
- World world Players: 0 total; []
- World world Chunk Stats: ServerChunkCache: 0 Drop: 0
- Type: Dedicated Server