A weird error?

I'd post this in "Bukkit Help", but I don't know if this is directly related to bukkit, my database, my host, or something else. So I'll post what I know, and the error itself, and hope someone knows what's causing it and how to fix it.

Bukkit Build: 1337
OS: Linux
Host: VeryGames

For the past day or so, my server would stop itself with this error:

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Code:

20:31:49 [SEVERE] java.util.ConcurrentModificationException
20:31:49 [SEVERE]      at java.util.AbstractList$Itr.checkForComodification(Abs
tractList.java:372)
20:31:49 [SEVERE]      at java.util.AbstractList$Itr.next(AbstractList.java:343
)
20:31:49 [SEVERE]      at java.util.AbstractCollection.removeAll(AbstractCollec
tion.java:336)
20:31:49 [SEVERE]      at net.minecraft.server.World.tickEntities(World.java:11
29)
20:31:49 [SEVERE]      at net.minecraft.server.MinecraftServer.h(MinecraftServe
r.java:467)
20:31:49 [SEVERE]      at net.minecraft.server.MinecraftServer.run(MinecraftSer
ver.java:374)
20:31:49 [SEVERE]      at net.minecraft.server.ThreadServerApplication.run(Sour
ceFile:417)
20:31:49 [SEVERE] Unexpected exception
java.util.ConcurrentModificationException
        at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:3
72)
        at java.util.AbstractList$Itr.next(AbstractList.java:343)
        at java.util.AbstractCollection.removeAll(AbstractCollection.java:336)
        at net.minecraft.server.World.tickEntities(World.java:1129)
        at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:467)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:374)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:417)

The weird thing, is the fact that it doesn't "crash" my server, but it tells it to stop, as I get the VeryGames stop message.

I've tried updating all my plugins, removing unused ones, and re-configuring some as well. It only happens sometimes, though. Any ideas?

 

"at net.minecraft.server.World.tickEntities(World.java:1129)"
I will guess that too many mobs have spawned.
Did you try any mob limiting plugins?

 

Just installed one and tried with no luck. It does seem like the issue is something alone those lines, though, as it's up for a bit before going down.