I tried Forge 1.3.3.14 and the same thing happened.Here is the full error log with all my mods as well.I made some Nano armor and it did the same thing.
Mods loaded: 29
ModLoader 1.1
mod_ModLoaderMp 1.0.0
mod_MinecraftForge 1.3.3.14
mod_NotEnoughItems 1.1.1
mod_treecapitator 1.1
mod_SwordsPlus 1.0
mod_BalkonInfiWeapons 0.10.4 InfiTools Edition
mod_BuildCraftCore 3.1.2
mod_BuildCraftBuilders 3.1.2
mod_BuildCraftEnergy 3.1.2
mod_BuildCraftFactory 3.1.2
mod_BuildCraftTransport 3.1.2
mod_BuildCraftSilicon 3.1.2
mod_zAdditionalPipes Rev34.0
mod_CraftGuide 1.4.1 for Minecraft 1.1.0
mod_DoggyTalents 1.0.0
mod_EE EE2 v1.0.0
mod_Flora 0.1.3 Berry
mod_IC2 v1.71
mod_BCIC2Crossover IBv0.05 for MC 1.1, BC 3.1.2, IC2 1.62
mod_QuickGuide 1.1
mod_RedPowerArray 2.0pr4d
mod_RedPowerCore 2.0pr4d
mod_RedPowerLighting 2.0pr4d
mod_RedPowerLogic 2.0pr4d
mod_RedPowerMachine 2.0pr4d
mod_RedPowerWiring 2.0pr4d
mod_RedPowerWorld 2.0pr4d
Balkon's WeaponMod 1.1.0 v8.3.0 Forge Edition
Minecraft has crashed!
----------------------
Minecraft has stopped running because it encountered a problem.
If you wish to report this, please copy this entire text and email it to support@mojang.com.
Please include a description of what you did when the error occured.
--- BEGIN ERROR REPORT 99f33724 --------
Generated 3/15/12 9:33 PM
Minecraft: Minecraft 1.1
OS: Windows XP (x86) version 5.1
Java: 1.7.0_01, Oracle Corporation
VM: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
LWJGL: 2.7.1
OpenGL: GeForce 7800 GT/PCI/SSE2 version 2.1.2, NVIDIA Corporation
java.lang.NoSuchMethodError: forge.ISpecialArmor.getProperties(Lxb;II)Lforge/ArmorProperties;
at xb.c(EntityPlayer.java:832)
at aar.a(EntityLiving.java:537)
at xb.a(EntityPlayer.java:744)
at xd.c(SourceFile:69)
at xd.a(SourceFile:75)
at yc.m_(EntityCreature.java:58)
at aar.d(EntityLiving.java:1036)
at xd.d(SourceFile:26)
at agy.d(SourceFile:48)
at aar.B_(EntityLiving.java:413)
at xd.B_(SourceFile:30)
at vq.a(World.java:1672)
at vq.f(World.java:1647)
at vq.m(World.java:1545)
at net.minecraft.client.Minecraft.k(SourceFile:1594)
at net.minecraft.client.Minecraft.x(SourceFile:709)
at net.minecraft.client.Minecraft.run(SourceFile:662)
at java.lang.Thread.run(Unknown Source)
--- END ERROR REPORT 4ec2cf7d ----------