Particular world won't load

[kmann100500]

Whenever I try to load a particular world the game just hangs on the loading screen, this is the crash report i get after closing mincraft.

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---- Minecraft Crash Report ----
// Don't be sad, have a hug! <3

Time: 25/11/13 21:24
Description: Exception in server tick loop

java.lang.ClassCastException: FCBlockStone cannot be cast to alb
at alc.<init>(SourceFile:33)
at alb.a(BlockRailBase.java:211)
at alb.a(BlockRailBase.java:132)
at abw.a(Chunk.java:659)
at aab.f(World.java:467)
at agw.a(SourceFile:384)
at agw.a(SourceFile:513)
at aen.a(ComponentMineshaftCorridor.java:339)
at agy.a(SourceFile:29)
at ags.a(SourceFile:73)
at acy.a(ChunkProviderGenerate.java:480)
at iy.a(ChunkProviderServer.java:233)
at abw.a(Chunk.java:1157)
at iy.c(ChunkProviderServer.java:128)
at net.minecraft.server.MinecraftServer.e(SourceFile:224)
at bjg.a(SourceFile:88)
at bjg.c(SourceFile:104)
at net.minecraft.server.MinecraftServer.run(SourceFile:306)
at gp.run(SourceFile:573)


A detailed walkthrough of the error, its code path and all known details is as follows:
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-- System Details --
Details:
Minecraft Version: 1.5.2
Operating System: Windows 7 (x86) version 6.1
Java Version: 1.7.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
Memory: 19128048 bytes (18 MB) / 76283904 bytes (72 MB) up to 518979584 bytes (494 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
Suspicious classes: FCBlockPistonExtension, FCBlockPistonMoving, FCBlockJackOLantern, ...]
IntCache: cache: 0, tcache: 0, allocated: 1, tallocated: 63
Profiler Position: N/A (disabled)
Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
Player Count: 0 / 8; []
Type: Integrated Server (map_client.txt)
Is Modded: Very likely; Jar signature invalidated

I have not changed anything with the install since I created the world and here is the list of mods i'm using.

BTW 4.9999999
BTW Research Add-On v1.1

[FlowerChild]

Don't file a bug report to try and get tech support again. A ban will most certainly result.