The following error occurs anytime someone joins the server. It's happened since updating to Vault version released on March 2, 2013. I removed plugins that were named in the error but it continues to happen. Error paste below:

2013-03-08 12:29:52 [INFO] madmanl01[/86.174.203.131:49920] logged in with entity id 952385 at ([Mystic] -855.4326255813799, 63.0, 1185.1709392007485)
2013-03-08 12:29:52 [SEVERE] Could not pass event PlayerJoinEvent to Vault v1.2.24-b304
org.bukkit.event.EventException
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:427)
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
at org.bukkit.plugin.TimedRegisteredListener.callEvent(TimedRegisteredListener.java:35)
at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
at net.minecraft.server.v1_4_R1.PlayerList.c(PlayerList.java:159)
at net.minecraft.server.v1_4_R1.PlayerList.a(PlayerList.java:98)
at net.minecraft.server.v1_4_R1.PendingConnection.d(PendingConnection.java:130)
at net.minecraft.server.v1_4_R1.PendingConnection.c(PendingConnection.java:45)
at net.minecraft.server.v1_4_R1.DedicatedServerConnectionThread.a(DedicatedServerConnectionThread.java:44)
at net.minecraft.server.v1_4_R1.DedicatedServerConnection.b(SourceFile:29)
at net.minecraft.server.v1_4_R1.MinecraftServer.r(MinecraftServer.java:598)
at net.minecraft.server.v1_4_R1.DedicatedServer.r(DedicatedServer.java:224)
at net.minecraft.server.v1_4_R1.MinecraftServer.q(MinecraftServer.java:494)
at net.minecraft.server.v1_4_R1.MinecraftServer.run(MinecraftServer.java:427)
at net.minecraft.server.v1_4_R1.ThreadServerApplication.run(SourceFile:849)
Caused by: java.lang.NoClassDefFoundError: de/bananaco/bpermissions/api/CalculableType
at net.milkbowl.vault.permission.plugins.Permission_bPermissions2.playerHas(Permission_bPermissions2.java:119)
at net.milkbowl.vault.permission.plugins.Permission_bPermissions2.has(Permission_bPermissions2.java:95)
at net.milkbowl.vault.Vault$VaultListener.onPlayerJoin(Vault.java:525)
at sun.reflect.GeneratedMethodAccessor525.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
... 15 more

You need to update bPerms.