What can cause Chunkerrors

Hi anyone has EXPLANATION for massive chunkerror?

Code:

net.minecraft.server.World.getTypeId(World.java:247)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.World.getEntities(World.java:942)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.Entity.move(Entity.java:453)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.EntityLiving.a(EntityLiving.java:657)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.EntityLiving.s(EntityLiving.java:810)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.EntityMonster.s(EntityMonster.java:27)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.EntityZombie.s(EntityZombie.java:30)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.EntityLiving.s_(EntityLiving.java:280)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.EntityMonster.s_(EntityMonster.java:31)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.World.entityJoinedWorld(World.java:1193)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.WorldServer.entityJoinedWorld(WorldServer.java:104)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.World.playerJoinedWorld(World.java:1175)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.World.tickEntities(World.java:1090)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:467)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:374)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.ThreadServerApplication.run(SourceFile:417)
2011-10-15 22:56:02 [SEVERE] Chunk (-17, -6) stored at  (-11, -9) in world 'CraftNatal-'
2011-10-15 22:56:02 [SEVERE] net.minecraft.server.Chunk
2011-10-15 22:56:02 [SEVERE] java.lang.Throwable
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.ChunkProviderServer.getOrCreateChunk(ChunkProviderServer.java:112)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.World.getChunkAt(World.java:300)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.World.getTypeId(World.java:247)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.World.getEntities(World.java:942)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.Entity.move(Entity.java:453)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.EntityLiving.a(EntityLiving.java:657)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.EntityLiving.s(EntityLiving.java:810)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.EntityMonster.s(EntityMonster.java:27)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.EntityZombie.s(EntityZombie.java:30)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.EntityLiving.s_(EntityLiving.java:280)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.EntityMonster.s_(EntityMonster.java:31)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.World.entityJoinedWorld(World.java:1193)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.WorldServer.entityJoinedWorld(WorldServer.java:104)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.World.playerJoinedWorld(World.java:1175)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.World.tickEntities(World.java:1090)
2011-10-15 22:56:02 [SEVERE]     at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:467)

 

Your map is corrupted. BACKUP THE MAP and run Chunkster.
http://forums.bukkit.org/threads/admin-chunkster.8186/

 

Thank you, you saved my life!