Updated minecraft to 1.4.7. Things were okay for a few minutes. went down in the mine, everything was going smooth. As soon as I broke through a wall to an area I had already escavated, the game crashed. I ctrl alt del. and closed the c-a-d window and minecraft had an error report. I attached the report from the file it designated. The window itself said this:
Minecraft has crashed!
----------------------

Minecraft has stopped running because it encountered a problem; Exception ticking world

A full error report has been saved to C:\Users\Chandler\AppData\Roaming\.minecraft\crash-reports\crash-2013-01-17_16.40.11-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 7193e06d --------
Full report at:
C:\Users\Chandler\AppData\Roaming\.minecraft\crash-reports\crash-2013-01-17_16.40.11-server.txt
Please show that file to Mojang, NOT just this screen!

Generated 1/17/13 4:40 PM

– Head –
Stacktrace:
at ii.a(SourceFile:69)
at ii.a(SourceFile:53)
at ij.a(SourceFile:24)
at yc.a(SourceFile:842)
at in.a(SourceFile:580)
at yc.d(SourceFile:834)
at yp.a(SourceFile:138)
at in.b(SourceFile:113)

– Affected level –
Details:
Level name: Atoll
All players: 1 total; [iq['chandlerj333'/248, l='Atoll', x=266.58, y=5.00, z=-55.10]]
Chunk stats: ServerChunkCache: 813 Drop: 0
Level seed: 63594748
Level generator: ID 00 - default, ver 1. Features enabled: true
Level generator options:
Level spawn location: World: (244,64,248), Chunk: (at 4,4,8 in 15,15; contains blocks 240,0,240 to 255,255,255), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 3393737 game time, 3991712 day time
Level dimension: 0
Level storage version: 0x04ABD - Anvil
Level weather: Rain time: 157136 (now: false), thunder time: 74402 (now: false)
Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
Stacktrace:
at net.minecraft.server.MinecraftServer.r(SourceFile:736)
at net.minecraft.server.MinecraftServer.q(SourceFile:679)
at bdz.q(SourceFile:117)
at net.minecraft.server.MinecraftServer.run(SourceFile:613)
at fy.run(SourceFile:849)

– System Details –
Details:
Minecraft Version: 1.4.7
Operating System: Windows 7 (x86) version 6.1
Java Version: 1.6.0_23, Sun Microsystems Inc.
Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Sun Microsystems Inc.
Memory: 249485960 bytes (237 MB) / 519110656 bytes (495 MB) up to 1037959168 bytes (989 MB)
JVM Flags: 2 total; -Xms512m -Xmx1024m
AABB Pool Size: 4515 (252840 bytes; 0 MB) allocated, 12 (672 bytes; 0 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: 7274 (407344 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
Player Count: 1 / 8; [iq['chandlerj333'/248, l='Atoll', x=266.58, y=5.00, z=-55.10]]
Type: Integrated Server (map_client.txt)
Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.

java.lang.IllegalStateException: Entity is already tracked!
at ii.a(SourceFile:69)
at ii.a(SourceFile:53)
at ij.a(SourceFile:24)
at yc.a(SourceFile:842)
at in.a(SourceFile:580)
at yc.d(SourceFile:834)
at yp.a(SourceFile:138)
at in.b(SourceFile:113)
at net.minecraft.server.MinecraftServer.r(SourceFile:736)
at net.minecraft.server.MinecraftServer.q(SourceFile:679)
at bdz.q(SourceFile:117)
at net.minecraft.server.MinecraftServer.run(SourceFile:613)
at fy.run(SourceFile:849)
— END ERROR REPORT b1cd24d9 ----------