[SOLVED]Support Request: SMP crashes at world gen

[SEVERE] Unexpected exception
java.lang.NullPointerException
at en.c(WorldServer.java:88)
at eh.b(World.java:855)
at qf.a(Block.java:290)
at qf.a(Block.java:273)
at qf.g(Block.java:260)
at lm.h(SourceFile:104)
at lm.a(SourceFile:91)
at eh.c(World.java:1031)
at lm.a(SourceFile:218)
at jf.a(Chunk.java:342)
at eh.a(World.java:267)
at eh.b(World.java:381)
at lm.a(SourceFile:81)
at eh.c(World.java:1031)
at lm.a(SourceFile:218)
at jf.a(Chunk.java:342)
at eh.a(World.java:267)
at eh.b(World.java:381)
at lm.a(SourceFile:81)
at eh.c(World.java:1031)
at lm.a(SourceFile:218)
at jf.a(Chunk.java:342)
at eh.a(World.java:267)
at eh.b(World.java:381)
at lm.a(SourceFile:81)
at eh.c(World.java:1031)
at lm.a(SourceFile:218)
at jf.a(Chunk.java:342)
at eh.a(World.java:267)
at eh.b(World.java:381)
at lm.a(SourceFile:81)
at eh.c(World.java:1031)
at lm.a(SourceFile:218)
at jf.a(Chunk.java:342)
at eh.a(World.java:267)
at eh.b(World.java:381)
at lm.a(SourceFile:82)
at eh.c(World.java:1031)
at lm.a(SourceFile:218)
at jf.a(Chunk.java:342)
at eh.a(World.java:267)
at eh.b(World.java:381)
at lm.h(SourceFile:107)
at lm.a(SourceFile:90)
at eh.c(World.java:1031)
at lm.a(SourceFile:218)
at jf.a(Chunk.java:342)
at eh.a(World.java:267)
at eh.b(World.java:381)
at lm.a(SourceFile:81)
at eh.c(World.java:1031)
at lm.a(SourceFile:218)
at jf.a(Chunk.java:342)
at eh.a(World.java:267)
at eh.b(World.java:381)
at lm.a(SourceFile:81)
at eh.c(World.java:1031)
at lm.a(SourceFile:218)
at jf.a(Chunk.java:342)
at eh.a(World.java:267)
at eh.b(World.java:381)
at lm.a(SourceFile:81)
at eh.c(World.java:1031)
at lm.a(SourceFile:218)
at jf.a(Chunk.java:342)
at eh.a(World.java:267)
at eh.b(World.java:381)
at lm.a(SourceFile:81)
at eh.c(World.java:1031)
at lm.a(SourceFile:218)
at jf.a(Chunk.java:342)
at eh.a(World.java:267)
at eh.b(World.java:381)
at lm.a(SourceFile:81)
at eh.c(World.java:1031)
at lm.a(SourceFile:218)
at jf.a(Chunk.java:342)
at eh.a(World.java:267)
at eh.b(World.java:381)
at lm.a(SourceFile:81)
at eh.c(World.java:1031)
at lm.a(SourceFile:218)
at jf.a(Chunk.java:342)
at eh.a(World.java:267)
at eh.b(World.java:381)
at lm.a(SourceFile:81)
at eh.c(World.java:1031)
at lm.a(SourceFile:218)
at jf.a(Chunk.java:342)
at eh.a(World.java:267)
at eh.b(World.java:381)
at lm.a(SourceFile:81)
at eh.c(World.java:1031)
at lm.a(SourceFile:218)
at jf.a(Chunk.java:342)
at eh.a(World.java:267)
at eh.b(World.java:381)
at lm.a(SourceFile:82)
at eh.c(World.java:1031)
at lm.a(SourceFile:218)
at jf.a(Chunk.java:342)
at eh.a(World.java:267)
at eh.b(World.java:381)
at lm.h(SourceFile:107)
at lm.a(SourceFile:92)
at td.a(SourceFile:36)
at fg.b(SourceFile:196)
at fg.a(SourceFile:27)
at il.a(SourceFile:180)
at to.a(SourceFile:484)
at ja.a(ChunkProviderServer.java:160)
at jf.a(Chunk.java:826)
at ja.c(ChunkProviderServer.java:74)
at ja.b(ChunkProviderServer.java:86)
at eh.c(World.java:248)
at eh.a(World.java:180)
at eh.f(World.java:186)
at eh.a(World.java:136)
at st.a(SourceFile:50)
at eh.c(World.java:122)
at eh.<init>(World.java:89)
at en.<init>(WorldServer.java:24)
at net.minecraft.server.MinecraftServer.a(MinecraftServer.java:156)
at net.minecraft.server.MinecraftServer.c(MinecraftServer.java:134)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:262)
at ce.run(SourceFile:417)