Another Error ClanWars5.5

2012-11-26 15:04:18 [SEVERE] Exception in thread "pool-1-thread-396"
2012-11-26 15:04:18 [SEVERE] org.apache.commons.lang.UnhandledException: Plugin ClanWars v5.5 generated an exception while executing task 13
	at org.bukkit.craftbukkit.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:56)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)
Caused by: java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(Unknown Source)
	at java.util.ArrayList$Itr.next(Unknown Source)
	at org.yaml.snakeyaml.serializer.Serializer.anchorNode(Serializer.java:142)
	at org.yaml.snakeyaml.serializer.Serializer.anchorNode(Serializer.java:146)
	at org.yaml.snakeyaml.serializer.Serializer.serialize(Serializer.java:108)
	at org.yaml.snakeyaml.Yaml.dumpAll(Yaml.java:271)
	at org.yaml.snakeyaml.Yaml.dumpAll(Yaml.java:261)
	at org.yaml.snakeyaml.Yaml.dumpAll(Yaml.java:233)
	at org.yaml.snakeyaml.Yaml.dump(Yaml.java:209)
	at org.bukkit.configuration.file.YamlConfiguration.saveToString(YamlConfiguration.java:38)
	at org.bukkit.configuration.file.FileConfiguration.save(FileConfiguration.java:54)
	at org.bukkit.plugin.java.JavaPlugin.saveConfig(JavaPlugin.java:129)
	at com.entrapmentserver.ClanWars.influenceIncrease(ClanWars.java:1223)
	at com.entrapmentserver.ClanWars.influenceTicker(ClanWars.java:1210)
	at com.entrapmentserver.ClanWars$1.run(ClanWars.java:75)
	at org.bukkit.craftbukkit.scheduler.CraftTask.run(CraftTask.java:53)
	at org.bukkit.craftbukkit.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:53)
	... 3 more