Failed to register dimension for id 0, One is already registered

[darkrising]

So I login onto to my server control panel to give the server its daily restart when it crashes with this error, as far as I'm aware dimension id 0 is the overworld, so what could be causing this?

Time: 11/13/12 2:00 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_59_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)

[DOUBLEPOST=1352815746][/DOUBLEPOST]oops I didn't see a topic of the same type below mine, sorry

http://forum.feed-the-beast.com/threads/dedicated-server-failing-to-start-mythcraft-related.1084/