I recently get a server lockup when commiting areas or even creating bigger ones.
For example I am only able to create a max. of 50x50 (otherwise it will never load the grid).

Sometimes at this point I have to restart the server...
After building something in the area I commit the plan and the server goes down again, after restarting the area is ready to get built.

I am using this neat plugin for several weeks now and I never had issues like that before!

My plugins are:

Bananabackup
Buildingplanner 0.5.0
CraftbukkitUpToDate (You should add your plugin here btw)
DwarfForge
EnderNerf
Essentials
NarrowTuxLib
Pail
PailPlus
PermissionsBukkit
PistonChest
Vehicle Exit
Spout
mChat

Server.log

2011-10-14 16:52:15 [INFO] Nagetier [/127.0.0.1:55144] logged in with entity id 96 at ([world_adv] -718.9723632549603, 67.0, 5.3387004208123825)
2011-10-14 16:52:16 [INFO] New max size: 484
2011-10-14 16:52:16 [INFO] New max size: 784
2011-10-14 16:52:28 [SEVERE] java.lang.NullPointerException
2011-10-14 16:52:28 [SEVERE] at java.util.TreeMap.rotateRight(Unknown Source)
2011-10-14 16:52:28 [SEVERE] at java.util.TreeMap.fixAfterInsertion(Unknown Source)
2011-10-14 16:52:28 [SEVERE] at java.util.TreeMap.put(Unknown Source)
2011-10-14 16:52:28 [SEVERE] at java.util.TreeSet.add(Unknown Source)
2011-10-14 16:52:28 [SEVERE] at net.minecraft.server.World.c(World.java:1035)
2011-10-14 16:52:28 [SEVERE] at net.minecraft.server.BlockSand.doPhysics(BlockSand.java:18)
2011-10-14 16:52:28 [SEVERE] at org.getspout.spout.block.mcblock.CustomBlock.doPhysics(CustomBlock.java:207)
2011-10-14 16:52:28 [SEVERE] at net.minecraft.server.World.k(World.java:488)
2011-10-14 16:52:28 [SEVERE] at net.minecraft.server.World.applyPhysics(World.java:468)
2011-10-14 16:52:28 [SEVERE] at net.minecraft.server.World.setData(World.java:375)
2011-10-14 16:52:28 [SEVERE] at org.bukkit.craftbukkit.block.CraftBlock.setData(CraftBlock.java:57)
2011-10-14 16:52:28 [SEVERE] at za.dats.bukkit.buildingplanner.ChangeScheduler$Change.apply(ChangeScheduler.java:37)
2011-10-14 16:52:28 [SEVERE] at za.dats.bukkit.buildingplanner.ChangeScheduler$ChangeExecutor.run(ChangeScheduler.java:50)
2011-10-14 16:52:28 [SEVERE] at org.bukkit.craftbukkit.scheduler.CraftWorker.run(CraftWorker.java:34)
2011-10-14 16:52:28 [SEVERE] at java.lang.Thread.run(Unknown Source)
2011-10-14 16:52:28 [SEVERE] java.lang.IllegalStateException: TickNextTick list out of synch
2011-10-14 16:52:28 [SEVERE] at net.minecraft.server.World.a(World.java:2122)
2011-10-14 16:52:28 [SEVERE] at net.minecraft.server.World.doTick(World.java:1637)
2011-10-14 16:52:28 [SEVERE] at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:461)
2011-10-14 16:52:28 [SEVERE] at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:374)
2011-10-14 16:52:28 [SEVERE] at net.minecraft.server.ThreadServerApplication.run(SourceFile:417)
2011-10-14 16:52:28 [SEVERE] Unexpected exception
java.lang.IllegalStateException: TickNextTick list out of synch
at net.minecraft.server.World.a(World.java:2122)
at net.minecraft.server.World.doTick(World.java:1637)
at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:461)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:374)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:417)

Hi there,

Try the latest dev build - I've done some work on getting the switching more stable. It places/removes the floor grid somewhat slower though, so don't just casually commit/uncommit large areas ;)

https://github.com/CmdrDats/BuildingPlanner/downloads