my minecraft keeps on crashing whenever i join my world the crash report is in the desc

i was making a map using mostly falling sand spawners i was exploiting 2 glitches one i was making a falling sand entity flass somehow to the old gostblocks bug thats all that ik here is my crash logg Minecraft has crashed!
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Minecraft has stopped running because it encountered a problem; Sending packet

A full error report has been saved to C:\Users\FTB Kingdom\AppData\Roaming\.minecraft\crash-reports\crash-2013-03-08_22.18.19-server.txt - Please include a copy of that file (Not this screen!) if you report this crash to anyone; without it, they will not be able to help fix the crash 😞

— BEGIN ERROR REPORT 5edc39cb --------
Full report at:
C:\Users\FTB Kingdom\AppData\Roaming\.minecraft\crash-reports\crash-2013-03-08_22.18.19-server.txt
Please show that file to Mojang, NOT just this screen!

Generated 3/8/13 10:18 PM

– Head –
Stacktrace:
at ch.b(SourceFile:107)
at ch.a(SourceFile:39)

– Packet being sent –
Details:
Packet ID: 4
Packet class: fh
Stacktrace:
at jh.b(SourceFile:430)
at gu.b(SourceFile:669)
at gu.a(SourceFile:79)
at bjd.b(SourceFile:73)
at net.minecraft.server.MinecraftServer.r(SourceFile:480)
at net.minecraft.server.MinecraftServer.q(SourceFile:397)
at bja.q(SourceFile:122)
at net.minecraft.server.MinecraftServer.run(SourceFile:331)
at gp.run(SourceFile:573)

– System Details –
Details:
Minecraft Version: 1.5
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.7.0_09, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 308562600 bytes (294 MB) / 930414592 bytes (887 MB) up to 954466304 bytes (910 MB)
JVM Flags: 2 total; -Xms512m -Xmx1024m
AABB Pool Size: 238158 (13336848 bytes; 12 MB) allocated, 238158 (13336848 bytes; 12 MB) used
Suspicious classes: No suspicious classes found.
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Profiler Position: N/A (disabled)
Vec3 Pool Size: 2 (112 bytes; 0 MB) allocated, 2 (112 bytes; 0 MB) used
Player Count: 0 / 8; []
Type: Integrated Server (map_client.txt)
Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.

java.lang.NullPointerException
at ch.b(SourceFile:107)
at ch.a(SourceFile:39)
at jh.b(SourceFile:430)
at gu.b(SourceFile:669)
at gu.a(SourceFile:79)
at bjd.b(SourceFile:73)
at net.minecraft.server.MinecraftServer.r(SourceFile:480)
at net.minecraft.server.MinecraftServer.q(SourceFile:397)
at bja.q(SourceFile:122)
at net.minecraft.server.MinecraftServer.run(SourceFile:331)
at gp.run(SourceFile:573)
— END ERROR REPORT 43839d12 ----------