Server wont start "Servere Unexpected Exception"

Code:

2011-01-20 00:19:27 [INFO] Stopping server
2011-01-20 00:21:31 [INFO] Starting minecraft server version Beta 1.2_01
2011-01-20 00:21:31 [INFO] Loading properties
2011-01-20 00:21:31 [INFO] Starting Minecraft server on *:25565
2011-01-20 00:21:31 [WARNING] **** SERVER IS RUNNING IN OFFLINE/INSECURE MODE!
2011-01-20 00:21:31 [WARNING] The server will make no attempt to authenticate usernames. Beware.
2011-01-20 00:21:31 [WARNING] While this makes the game possible to play without internet access, it also opens up the ability for hackers to connect with any username they choose.
2011-01-20 00:21:31 [WARNING] To change this, set "online-mode" to "true" in the server.settings file.
2011-01-20 00:21:31 [INFO] Preparing level "world"
2011-01-20 00:21:31 [INFO] Preparing start region
2011-01-20 00:21:32 [SEVERE] Unexpected exception
java.lang.NullPointerException
    at net.minecraft.server.WorldServer.b(WorldServer.java:80)
    at net.minecraft.server.World.a(SourceFile:1659)
    at net.minecraft.server.Chunk.d(SourceFile:480)
    at net.minecraft.server.ChunkProviderServer.d(ChunkProviderServer.java:69)
    at net.minecraft.server.ChunkProviderServer.b(ChunkProviderServer.java:108)
    at net.minecraft.server.World.c(SourceFile:417)
    at net.minecraft.server.World.a(SourceFile:374)
    at net.minecraft.server.World.e(SourceFile:378)
    at net.minecraft.server.World.a(SourceFile:282)
    at net.minecraft.server.WorldProvider.a(SourceFile:52)
    at net.minecraft.server.World.<init>(SourceFile:255)
    at net.minecraft.server.WorldServer.<init>(WorldServer.java:24)
    at net.minecraft.server.MinecraftServer.c(MinecraftServer.java:111)
    at net.minecraft.server.MinecraftServer.d(MinecraftServer.java:104)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:177)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:512)

Anybody know why my server wont start?

 

what bukkit build are you using? Looks like a corrupt or incompatible world/jar

 

Backup that world folder and try it with a fresh map. As said above, could be a corrupt map.

 

My server does this, but when like 1-60 minutes of running time