Bukkit failed to set data for last duc time

Hello, I am having a error with bukkit, i dont know what to do.
First I was thinking that the error was something with the gui I was using, but after I switched the gui, the same happened again.
I got many windows one on top another with the message:
bukkit failed to set data for last duc time
Here is the log part that describes the error.

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2011-09-04 04:18:07 [INFO] Starting minecraft server version Beta 1.7.3
2011-09-04 04:18:07 [INFO] Loading properties
2011-09-04 04:18:07 [INFO] Starting Minecraft server on *:25565
2011-09-04 04:18:07 [INFO] This server is running Craftbukkit version git-Bukkit-0.0.0-980-g4ed23b1-b1060jnks (MC: 1.7.3)
2011-09-04 04:18:08 [INFO] LWC: Loading shared objects
2011-09-04 04:18:08 [INFO] LWC: Protection cache: 0/10000
2011-09-04 04:18:08 [INFO] LWC: Native library: plugins/LWC/lib/native/Windows/x86/sqlitejdbc.dll
2011-09-04 04:18:08 [INFO] Preparing level "Multi"
2011-09-04 04:18:09 [INFO] Preparing start region for level 0 (Seed: 4615791261332968584)
2011-09-04 04:18:10 [INFO] Preparing spawn area: 28%
2011-09-04 04:18:11 [INFO] Preparing spawn area: 73%
2011-09-04 04:18:11 [INFO] Preparing start region for level 1 (Seed: -3199651873637437744)
2011-09-04 04:18:12 [INFO] Preparing spawn area: 32%
2011-09-04 04:18:13 [INFO] Preparing spawn area: 85%
2011-09-04 04:18:14 [INFO] BS-GUIPlugin version 1.1 is enabled!
2011-09-04 04:18:14 [INFO] [GiveMeWool] Booting...
2011-09-04 04:18:14 [WARNING] [GiveMeWool] Permissions system not detected! Defaulting to OP!
2011-09-04 04:18:14 [INFO] [GiveMeWool] Done!
2011-09-04 04:18:14 [INFO] [HealthBar] Loading..
2011-09-04 04:18:14 [INFO] [HealthBar] Loaded up plugin... Version 0.7.
2011-09-04 04:18:14 [INFO] [HeroicDeath] 1.9.1 enabled.
2011-09-04 04:18:14 [INFO] MCBukkitManager version 1.2 is enabled!
2011-09-04 04:18:15 [INFO] Spout 1.0.5.227 has been initialized
2011-09-04 04:18:15 [INFO] [Achievement] 3co not found.
2011-09-04 04:18:15 [INFO] [Achievement] iConomy not found.
2011-09-04 04:18:15 [INFO] [Achievement] Version 1.3 by IC3D enabled
2011-09-04 04:18:15 [INFO] [Achievement] Test query sccessful: captainawesome7 has broken air 1 times
2011-09-04 04:18:15 [INFO] LWC: Loaded 137 locale strings (0 overrides)
2011-09-04 04:18:15 [INFO] LWC: Permissions API: NoPermissions
2011-09-04 04:18:15 [INFO] LWC: Currency API: NoCurrency
2011-09-04 04:18:15 [INFO] LWC: Loading SQLite
2011-09-04 04:18:15 [INFO] LWC: Using: Native
2011-09-04 04:18:15 [INFO] LWC: Precached 9 protections.
2011-09-04 04:18:15 [INFO] LWC: At version: 3,42 (b154)
2011-09-04 04:18:15 [INFO] Server permissions file permissions.yml is empty, ignoring it
2011-09-04 04:18:15 [INFO] Done (0,700s)! For help, type "help" or "?"
2011-09-04 04:18:21 [WARNING] Can't keep up! Did the system time change, or is the server overloaded?
2011-09-04 09:33:23 [SEVERE] net.minecraft.server.MinecraftException: Failed to check session lock, aborting
2011-09-04 09:33:23 [SEVERE] at net.minecraft.server.PlayerNBTManager.b(PlayerNBTManager.java:71)
2011-09-04 09:33:23 [SEVERE] at net.minecraft.server.World.k(World.java:2258)
2011-09-04 09:33:23 [SEVERE] at net.minecraft.server.World.w(World.java:221)
2011-09-04 09:33:23 [SEVERE] at net.minecraft.server.World.save(World.java:211)
2011-09-04 09:33:23 [SEVERE] at net.minecraft.server.World.doTick(World.java:1732)
2011-09-04 09:33:23 [SEVERE] at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:444)
2011-09-04 09:33:23 [SEVERE] at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:363)
2011-09-04 09:33:23 [SEVERE] at net.minecraft.server.ThreadServerApplication.run(SourceFile:422)
2011-09-04 09:33:23 [SEVERE] Unexpected exception
net.minecraft.server.MinecraftException: Failed to check session lock, aborting
at net.minecraft.server.PlayerNBTManager.b(PlayerNBTManager.java:71)
at net.minecraft.server.World.k(World.java:2258)
at net.minecraft.server.World.w(World.java:221)
at net.minecraft.server.World.save(World.java:211)
at net.minecraft.server.World.doTick(World.java:1732)
at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:444)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:363)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:422)

Plugins that I use:
HealthBar
Achievement
HeroicDeath
LWC
MC Bukkit Manager
Spout

And I am using a spout client too.

Please someone help!