Bukkit fehlermeldung !

Bei meinen bukkit sever kommen nach 10 minuten diese fehler am laufenden band

File:28)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.World.a(World.java:2111)

14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.EntityCreature.B(EntityC
reature.java:177)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.EntityCreature.c_(Entity
Creature.java:73)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.EntityLiving.v(EntityLiv
ing.java:685)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.EntityLiving.m_(EntityLi
ving.java:218)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.World.entityJoinedWorld(
World.java:1190)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.WorldServer.entityJoined
World(WorldServer.java:48)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.World.playerJoinedWorld(
World.java:1172)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.World.cleanUp(World.java
:1102)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.MinecraftServer.h(Minecr
aftServer.java:447)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.MinecraftServer.run(Mine
craftServer.java:361)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.ThreadServerApplication.
run(SourceFile:422)
14:01:29 [INFO] Chunk (10, -27) stored at  (6, -12)
14:01:29 [INFO] net.minecraft.server.Chunk
14:01:29 [SCHWERWIEGEND] java.lang.Throwable
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.ChunkProviderServer.getO
rCreateChunk(ChunkProviderServer.java:124)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.World.getChunkAt(World.j
ava:272)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.ChunkCache.<init>(Source
File:28)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.World.a(World.java:2111)

14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.EntityCreature.B(EntityC
reature.java:177)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.EntityCreature.c_(Entity
Creature.java:73)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.EntityLiving.v(EntityLiv
ing.java:685)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.EntityLiving.m_(EntityLi
ving.java:218)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.World.entityJoinedWorld(
World.java:1190)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.WorldServer.entityJoined
World(WorldServer.java:48)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.World.playerJoinedWorld(
World.java:1172)
14:01:29 [SCHWERWIEGEND]        at net.minecraft.server.World.cleanUp(World.java

und es hört nicht auf und dan fliegen wir nach ca 30 min raus