IMPORTANT I AM RUNNING MINECRAFT 1.7.2!!!!!!!!!!!!!!!!!!

---- Minecraft Crash Report ----
// Sorry

Time: 4/20/14 3:48 PM
Description: Ticking entity

java.lang.ClassCastException: cannot be cast to ayf
at ayh.a(SourceFile:26)
at ahu.a(SourceFile:602)
at ahu.a(SourceFile:597)
at afn.a(SourceFile:958)
at qn.d(SourceFile:497)
at rh.e(SourceFile:1125)
at rh.e(SourceFile:1350)
at ri.e(SourceFile:295)
at rh.h(SourceFile:1205)
at ri.h(SourceFile:171)
at uq.h(SourceFile:109)
at afn.a(SourceFile:1368)
at mj.a(SourceFile:480)
at afn.g(SourceFile:1346)
at afn.h(SourceFile:1253)
at mj.h(SourceFile:365)
at net.minecraft.server.MinecraftServer.u(SourceFile:511)
at net.minecraft.server.MinecraftServer.t(SourceFile:441)
at bsk.t(SourceFile:117)
at net.minecraft.server.MinecraftServer.run(SourceFile:358)
at ky.run(SourceFile:617)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

– Head –
Stacktrace:
at ayh.a(SourceFile:26)
at ahu.a(SourceFile:602)
at ahu.a(SourceFile:597)
at afn.a(SourceFile:958)
at qn.d(SourceFile:497)
at rh.e(SourceFile:1125)
at rh.e(SourceFile:1350)
at ri.e(SourceFile:295)
at rh.h(SourceFile:1205)
at ri.h(SourceFile:171)
at uq.h(SourceFile:109)
at afn.a(SourceFile:1368)
at mj.a(SourceFile:480)
at afn.g(SourceFile:1346)

– Entity being ticked –
Details:
Entity Type: Bat (uq)
Entity ID: 1286758
Entity Name: Bat
Entity's Exact location: 963.68, 34.10, 572.75
Entity's Block location: World: (963,34,572), Chunk: (at 3,2,12 in 60,35; contains blocks 960,0,560 to 975,255,575), Region: (1,1; contains chunks 32,32 to 63,63, blocks 512,0,512 to 1023,255,1023)
Entity's Momentum: 0.00, 0.00, 0.00
Stacktrace:
at afn.h(SourceFile:1253)
at mj.h(SourceFile:365)

– Affected level –
Details:
Level name: Alex's Survival
All players: 1 total; [mm['HyperCamel'/1280344, l='Alex's Survival', x=949.30, y=72.00, z=483.83]]
Chunk stats: ServerChunkCache: 1066 Drop: 0
Level seed: -6414032518512847293
Level generator: ID 00 - default, ver 1. Features enabled: true
Level generator options:
Level spawn location: World: (176,64,44), Chunk: (at 0,4,12 in 11,2; contains blocks 176,0,32 to 191,255,47), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 566468 game time, 786101 day time
Level dimension: 0
Level storage version: 0x04ABD - Anvil
Level weather: Rain time: 50552 (now: false), thunder time: 148526 (now: false)
Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
Stacktrace:
at net.minecraft.server.MinecraftServer.u(SourceFile:511)
at net.minecraft.server.MinecraftServer.t(SourceFile:441)
at bsk.t(SourceFile:117)
at net.minecraft.server.MinecraftServer.run(SourceFile:358)
at ky.run(SourceFile:617)

– System Details –
Details:
Minecraft Version: 1.7.2
Operating System: Windows 7 (x86) version 6.1
Java Version: 1.7.0_51, Oracle Corporation
Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
Memory: 218047576 bytes (207 MB) / 482488320 bytes (460 MB) up to 518979584 bytes (494 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
AABB Pool Size: 5703 (319368 bytes; 0 MB) allocated, 4171 (233576 bytes; 0 MB) used
IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
Profiler Position: N/A (disabled)
Vec3 Pool Size: 1520 (85120 bytes; 0 MB) allocated, 619 (34664 bytes; 0 MB) used
Player Count: 1 / 8; [mm['HyperCamel'/1280344, l='Alex's Survival', x=949.30, y=72.00, z=483.83]]
Type: Integrated Server (map_client.txt)
Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.

This is the error report if one of you Mojang people can help me