Not sure why I am getting this start up Error.

2012-04-22 18:35:32 [INFO] [PreciousStones] Enabling PreciousStones v9.1.0
2012-04-22 18:35:32 [INFO] [PreciousStones] Version 9.1.0 loaded
2012-04-22 18:35:32 [SEVERE] Error occurred while enabling PreciousStones v9.1.0 (Is it up to date?)
java.lang.ClassCastException: java.util.ArrayList cannot be cast to java.lang.String
at net.sacredlabyrinth.Phaed.PreciousStones.FieldSettings.(FieldSettings.java:79)
at net.sacredlabyrinth.Phaed.PreciousStones.managers.SettingsManager.addForceFieldStones(SettingsManager.java:297)
at net.sacredlabyrinth.Phaed.PreciousStones.managers.SettingsManager.load(SettingsManager.java:264)
at net.sacredlabyrinth.Phaed.PreciousStones.managers.SettingsManager.(SettingsManager.java:134)
at net.sacredlabyrinth.Phaed.PreciousStones.PreciousStones.onEnable(PreciousStones.java:117)
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:215)
at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:336)
at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:381)
at org.bukkit.craftbukkit.CraftServer.loadPlugin(CraftServer.java:250)
at org.bukkit.craftbukkit.CraftServer.enablePlugins(CraftServer.java:232)
at net.minecraft.server.MinecraftServer.t(MinecraftServer.java:371)
at net.minecraft.server.MinecraftServer.a(MinecraftServer.java:358)
at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:187)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:422)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)