[Urgent] Faction 'Cleanup' erased data.

Players on my server have been complaining that all their factions are gone, so I looked in the to issue. When looking in the server logs, I see this error appear at least 20 times.

Code:

2012-09-05 16:47:22 [WARNING] [Factions v1.6.9] Non existing factionId 0 requested! Issuing cleaning!
2012-09-05 16:47:22 [INFO] [Factions v1.6.9] Reset faction data (invalid faction) for player **USERNAME**
2012-09-05 16:47:22 [INFO] [Factions v1.6.9] Reset faction data (invalid faction) for player **USERNAME**
2012-09-05 16:47:22 [INFO] [Factions v1.6.9] Reset faction data (invalid faction) for player **USERNAME**
2012-09-05 16:47:22 [INFO] [Factions v1.6.9] Reset faction data (invalid faction) for player **USERNAME**
2012-09-05 16:47:22 [INFO] [Factions v1.6.9] Reset faction data (invalid faction) for player **USERNAME**
2012-09-05 16:47:22 [INFO] [Factions v1.6.9] Reset faction data (invalid faction) for player **USERNAME**
2012-09-05 16:47:22 [INFO] [Factions v1.6.9] Reset faction data (invalid faction) for player **USERNAME**
2012-09-05 16:47:22 [INFO] [Factions v1.6.9] Reset faction data (invalid faction) for player **USERNAME**
2012-09-05 16:47:22 [INFO] [Factions v1.6.9] Reset faction data (invalid faction) for player **USERNAME**
2012-09-05 16:47:22 [INFO] [Factions v1.6.9] Reset faction data (invalid faction) for player **USERNAME**
2012-09-05 16:47:22 [INFO] [Factions v1.6.9] Reset faction data (invalid faction) for player **USERNAME**
2012-09-05 16:47:22 [SEVERE] Could not pass event CreatureSpawnEvent to Factions
org.bukkit.event.EventException
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:332)
    at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
    at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
    at org.bukkit.craftbukkit.event.CraftEventFactory.callCreatureSpawnEvent(CraftEventFactory.java:226)
    at net.minecraft.server.World.addEntity(World.java:837)
    at net.minecraft.server.SpawnerCreature.spawnEntities(SpawnerCreature.java:175)
    at net.minecraft.server.WorldServer.doTick(WorldServer.java:154)
    at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:560)
    at net.minecraft.server.DedicatedServer.q(DedicatedServer.java:212)
    at net.minecraft.server.MinecraftServer.p(MinecraftServer.java:476)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:408)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:539)
Caused by: java.lang.NullPointerException
    at com.massivecraft.factions.listeners.FactionsEntityListener.onCreatureSpawn(FactionsEntityListener.java:453)
    at sun.reflect.GeneratedMethodAccessor35.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:330)
    ... 12 more

After this, all of the faction data (factions.json) has been erased.

Can anyone help me with this problem? What caused it, and is there a way to fix it? If not how can I prevent this in the future?

Any and all help is appreciated!

Thanks,
NXTGUY

Does anyone have a idea of what happend?

EDIT by Moderator: merged posts, please use the edit button instead of double posting.