Random crash

CRASH REPORT:

— BEGIN ERROR REPORT 3d5a5a2 --------

Generated 3/19/13 7:11 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: Mac OS X (x86_64) version 10.8.2
Java Version: 1.6.0_37, Apple Inc.
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
Memory: 167627504 bytes (159 MB) / 656084992 bytes (625 MB) up to 1065025536 bytes (1015 MB)
JVM Flags: 3 total; -Xbootclasspath/a:/System/Library/PrivateFrameworks/JavaApplicationLauncher.framework/Resources/LauncherSupport.jar -Xms512M -Xmx1024M
AABB Pool Size: 447635 (25067560 bytes; 23 MB) allocated, 447635 (25067560 bytes; 23 MB) used
Suspicious classes: No suspicious classes found.
IntCache: cache: 0, tcache: 0, allocated: 1, tallocated: 63
Profiler Position: N/A (disabled)
Vec3 Pool Size: 59754 (3346224 bytes; 3 MB) allocated, 59754 (3346224 bytes; 3 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 96623b29 ----------