Bukkit

What steps will reproduce the problem?
1. Error appears at random intervals, 10 to 30 players on, hard to tell.
2.
3.

What is the expected output? What do you see instead?
Cause bleeding effect without error/lag

What version of the product are you using?
4.4 Latest

Do you have an error log of what happened?
2013-07-28 05:30:41 [WARNING] [BleedingMobs] Task #150339 for BleedingMobs v4.4 generated an exception
java.lang.IllegalStateException
    at me.snowleo.bleedingmobs.particles.Items.removeFromLimit(Items.java:104)
    at me.snowleo.bleedingmobs.particles.Items.remove(Items.java:69)
    at me.snowleo.bleedingmobs.tasks.ParticleStateTask.run(ParticleStateTask.java:63)
    at org.bukkit.craftbukkit.v1_6_R2.scheduler.CraftTask.run(CraftTask.java:58)
    at org.bukkit.craftbukkit.v1_6_R2.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:345)
    at net.minecraft.server.v1_6_R2.MinecraftServer.t(MinecraftServer.java:518)
    at net.minecraft.server.v1_6_R2.DedicatedServer.t(DedicatedServer.java:239)
    at net.minecraft.server.v1_6_R2.MinecraftServer.s(MinecraftServer.java:481)
    at net.minecraft.server.v1_6_R2.MinecraftServer.run(MinecraftServer.java:413)
    at net.minecraft.server.v1_6_R2.ThreadServerApplication.run(SourceFile:582)
2013-07-28 05:30:41 [INFO] Item at Location{world=CraftWorld{name=world},x=341.9636162737381,y=4.741800007742643,z=2802.090761417576,pitch=0.0,yaw=172.01523} with value ItemStack{REDSTONE x 1, UNSPECIFIC_META:{meta-type=UNSPECIFIC, enchants={DURABILITY=2779}}}
2013-07-28 05:30:41 [WARNING] [BleedingMobs] Task #150342 for BleedingMobs v4.4 generated an exception
java.lang.IllegalStateException
    at me.snowleo.bleedingmobs.particles.Items.removeFromLimit(Items.java:104)
    at me.snowleo.bleedingmobs.particles.Items.remove(Items.java:69)
    at me.snowleo.bleedingmobs.tasks.ParticleStateTask.run(ParticleStateTask.java:63)
    at org.bukkit.craftbukkit.v1_6_R2.scheduler.CraftTask.run(CraftTask.java:58)
    at org.bukkit.craftbukkit.v1_6_R2.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:345)
    at net.minecraft.server.v1_6_R2.MinecraftServer.t(MinecraftServer.java:518)
    at net.minecraft.server.v1_6_R2.DedicatedServer.t(DedicatedServer.java:239)
    at net.minecraft.server.v1_6_R2.MinecraftServer.s(MinecraftServer.java:481)
    at net.minecraft.server.v1_6_R2.MinecraftServer.run(MinecraftServer.java:413)
    at net.minecraft.server.v1_6_R2.ThreadServerApplication.run(SourceFile:582)

Please provide any additional information below.
Running Spigot and Crackshot guns plugin to cause entity damage with McMMO for skills/leveling