Furnace Crash

Hey, so my server has just crashed. I've tried putting a redwood log into a furnace, and tried smelting it with a redwood log.

I have tried removing all of my plugins. I still have the same problem.

Here is my error message:

Code:

[WARNING] Failed to handle packet: java.lang.NullPointerException
java.lang.NullPointerException
    at net.minecraft.server.ItemStack.d(ItemStack.java:95)
    at net.minecraft.server.ItemStack.f(ItemStack.java:103)
    at net.minecraft.server.InventoryPlayer.pickup(InventoryPlayer.java:142)
    at net.minecraft.server.EntityItem.b(EntityItem.java:144)
    at net.minecraft.server.EntityHuman.i(EntityHuman.java:219)
    at net.minecraft.server.EntityHuman.v(EntityHuman.java:211)
    at net.minecraft.server.EntityPlayer.v(EntityPlayer.java:280)
    at net.minecraft.server.EntityLiving.m_(EntityLiving.java:218)
    at net.minecraft.server.EntityHuman.m_(EntityHuman.java:96)
    at net.minecraft.server.EntityPlayer.a(EntityPlayer.java:192)
    at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:294)
    at net.minecraft.server.Packet10Flying.a(SourceFile:126)
    at net.minecraft.server.NetworkManager.b(NetworkManager.java:226)
    at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:85)
    at net.minecraft.server.NetworkListenThread.a(SourceFile:105)
    at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:451)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:361)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:422)
2011-08-04 01:41:22 [INFO] Connection reset

I'm using Bukkit build 1000. This may be an error with Lockcraft, but I don't see how when it persists with all plugins off.