Bukkit

2013-06-11 10:28:28 [INFO] [Seasons] Seasons in Mischivia changes to Winter.
2013-06-11 10:28:31 [SEVERE] Exception in thread "Seasons-SnowThread"
2013-06-11 10:28:31 [SEVERE] java.util.ConcurrentModificationException
2013-06-11 10:28:31 [SEVERE]     at org.bukkit.craftbukkit.v1_5_R3.util.LongObjectHashMap$ValueIterator.next(LongObjectHashMap.java:299)
2013-06-11 10:28:31 [SEVERE]     at java.util.AbstractCollection.toArray(AbstractCollection.java:141)
2013-06-11 10:28:31 [SEVERE]     at org.bukkit.craftbukkit.v1_5_R3.CraftWorld.getLoadedChunks(CraftWorld.java:131)
2013-06-11 10:28:31 [SEVERE]     at org.rominos2.Seasons.Managers.SnowManager.SeasonsSnowThread.run(SeasonsSnowThread.java:71)

using latest bukkit and libs etc

here's my world config file:

Seasons:
  Spring:
    Visual:
      Textures: ''
      Snow: 25
    ShortName: spring
    Lengths:
      Season: 5.0
      Weather: 0.2
    Percentages:
      Sun: 25
      Rain: 10
      Thunder: 2
    SpecialDays:
      '1': Spring! The Land rejoices!
    SnowManagerSpeed:
      Place: 0
      Remove: 0.1
    Time:
      Day: 13000
      Night: 10000
  Summer:
    Visual:
      Textures: ''
      Snow: 0
    ShortName: summer
    Lengths:
      Season: 10.0
      Weather: 0.5
    Percentages:
      Sun: 70
      Rain: 20
      Thunder: 10
    SpecialDays:
      '1': Summer! Time to bust out the pool!
    SnowManagerSpeed:
      Place: 0
      Remove: 0.2
    Time:
      Day: 15000
      Night: 9000
  Autumn:
    Visual:
      Textures: ''
      Snow: 25
    ShortName: autumn
    Lengths:
      Season: 5.0
      Weather: 0.2
    Percentages:
      Sun: 50
      Rain: 30
      Thunder: 5
    SpecialDays:
      '1': Autumn! The Leaves a leaving!
    SnowManagerSpeed:
      Place: 0.1
      Remove: 0.1
    Time:
      Day: 13000
      Night: 10000
  Winter:
    Visual:
      Textures: ''
      Snow: 100
    ShortName: winter
    Lengths:
      Season: 10.0
      Weather: 0.5
    Percentages:
      Sun: 30
      Rain: 60
      Thunder: 10
    SpecialDays:
      '1': Winter! Let it snow let it snow let it snow!
    SnowManagerSpeed:
      Place: 0.3
      Remove: 0.1
    Time:
      Day: 12000
      Night: 11000
Properties:
  Active: true
  LogInfo: true
  Resolution:
    Precision: 0.01
    TimeCheck: 20
  Regen:
    Snow: true
    Ice: true
  Messages:
    ChangeMessage: Seasons changes to <name>.
    SeasonsMessage: You're in <name> for another <number> days.
    SpecialDayMessage: It's <name>.
    Weather: The current weather is <name>.
    Color: b
    NotActive: Seasons are not active in this world.
    Sign:
    - <name>
    - Day <day>
    - Of <length>
    ColorList:
      BLACK: '0'
      DARK_BLUE: '1'
      DARK_GREEN: '2'
      DARK_AQUA: '3'
      DARK_RED: '4'
      DARK_PURPLE: '5'
      GOLD: '6'
      GRAY: '7'
      DARK_GRAY: '8'
      BLUE: '9'
      GREEN: a
      AQUA: b
      RED: c
      LIGHT_PURPLE: d
      YELLOW: e
      WHITE: f
      MAGIC: k
      BOLD: l
      STRIKETHROUGH: m
      UNDERLINE: n
      ITALIC: o
      RESET: r
  Debug: false

Cheers