Server crashes for no reason + error

So i get this error

Code:

10.01 14:11:03 [Server] SEVERE     at java.lang.Thread.run(Thread.java:722)
10.01 14:11:03 [Server] SEVERE     at org.bukkit.craftbukkit.scheduler.CraftWorker.run(CraftWorker.java:34)
10.01 14:11:03 [Server] SEVERE     at com.earth2me.essentials.storage.AbstractDelayedYamlFileReader.run(AbstractDelayedYamlFileReader.java:38)
10.01 14:11:03 [Server] SEVERE     at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
10.01 14:11:03 [Server] SEVERE     at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
10.01 14:11:03 [Server] SEVERE     at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:24)
10.01 14:11:03 [Server] SEVERE     at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:32)
10.01 14:11:03 [Server] SEVERE     at org.bukkit.plugin.java.JavaPluginLoader.getClassByName(JavaPluginLoader.java:217)
10.01 14:11:03 [Server] SEVERE     at java.util.HashMap$KeyIterator.next(HashMap.java:841)
10.01 14:11:03 [Server] SEVERE     at java.util.HashMap$HashIterator.nextEntry(HashMap.java:806)
10.01 14:11:03 [Server] SEVERE java.util.ConcurrentModificationException

and i don't know which plugin is causing it!it makes my server crash really fast and i don't know how to fix it

i think there is a problem with WEPIF cause i use bPermissions and i think it doesn't like something from WorldEdit

 

That isnt the full error. Can you post the full server log?

 

In addition to what Zaros said, please can you tell us which plugins you have installed?
Thanks