I have the same problem, it happens right after the Minecraft Logo.
My crash report:
===Simple Minecraft Error Test===
Starting Minecraft...
2012-09-08 18:38:35 [iNFO] [ForgeModLoader] Forge Mod Loader version 3.0.148.332
for Minecraft client:1.3.2, server:1.3.2 loading
2012-09-08 18:38:36 [iNFO] [sTDOUT] 27 achievements
2012-09-08 18:38:36 [iNFO] [sTDOUT] 195 recipes
2012-09-08 18:38:36 [iNFO] [sTDOUT] Setting user: Playa, -
2012-09-08 18:38:36 [iNFO] [sTDERR] Client asked for parameter: server
2012-09-08 18:38:36 [iNFO] [sTDOUT] LWJGL Version: 2.4.2
2012-09-08 18:38:37 [iNFO] [ForgeModLoader] Attempting early MinecraftForge init
ialization
2012-09-08 18:38:37 [iNFO] [ForgeModLoader] Completed early MinecraftForge initi
alization
2012-09-08 18:38:37 [iNFO] [ForgeModLoader] Searching C:\Users\Anthony\AppData\R
oaming\.minecraft\mods for mods
2012-09-08 18:38:37 [iNFO] [ForgeModLoader] The mod container minecraft.jar appe
ars to be missing an mcmod.info file
2012-09-08 18:38:38 [iNFO] [ForgeModLoader] No mcmod.info file found in director
y 1.2.5
2012-09-08 18:38:38 [iNFO] [ForgeModLoader] No mcmod.info file found in director
y portalgun
2012-09-08 18:38:38 [iNFO] [ForgeModLoader] No mcmod.info file found in director
y rei_minimap
2012-09-08 18:38:38 [iNFO] [ForgeModLoader] No mcmod.info file found in director
y sppcommands
2012-09-08 18:38:38 [iNFO] [ForgeModLoader] Forge Mod Loader has identified 3 mo
ds to load
2012-09-08 18:38:38 [iNFO] [sTDERR] Exception in thread "Minecraft main thread"
java.lang.NoClassDefFoundError: Portal_TextureAnimation
2012-09-08 18:38:38 [iNFO] [sTDERR] at java.lang.Class.forName0(Native Metho
d)
2012-09-08 18:38:38 [iNFO] [sTDERR] at java.lang.Class.forName(Unknown Sourc
e)
2012-09-08 18:38:38 [iNFO] [sTDERR] at cpw.mods.fml.common.modloader.ModLoad
erModContainer.constructMod(ModLoaderModContainer.java:488)
2012-09-08 18:38:38 [iNFO] [sTDERR] at sun.reflect.NativeMethodAccessorImpl.
invoke0(Native Method)
2012-09-08 18:38:38 [iNFO] [sTDERR] at sun.reflect.NativeMethodAccessorImpl.
invoke(Unknown Source)
2012-09-08 18:38:38 [iNFO] [sTDERR] at sun.reflect.DelegatingMethodAccessorI
mpl.invoke(Unknown Source)
2012-09-08 18:38:38 [iNFO] [sTDERR] at java.lang.reflect.Method.invoke(Unkno
wn Source)
2012-09-08 18:38:38 [iNFO] [sTDERR] at com.google.common.eventbus.EventHandl
er.handleEvent(EventHandler.java:69)
2012-09-08 18:38:38 [iNFO] [sTDERR] at com.google.common.eventbus.Synchroniz
edEventHandler.handleEvent(SynchronizedEventHandler.java:45)
2012-09-08 18:38:38 [iNFO] [sTDERR] at com.google.common.eventbus.EventBus.d
ispatch(EventBus.java:317)
2012-09-08 18:38:38 [iNFO] [sTDERR] at com.google.common.eventbus.EventBus.d
ispatchQueuedEvents(EventBus.java:300)
2012-09-08 18:38:38 [iNFO] [sTDERR] at com.google.common.eventbus.EventBus.p
ost(EventBus.java:268)
2012-09-08 18:38:38 [iNFO] [sTDERR] at cpw.mods.fml.common.LoadController.pr
opogateStateMessage(LoadController.java:123)
2012-09-08 18:38:38 [iNFO] [sTDERR] at sun.reflect.NativeMethodAccessorImpl.
invoke0(Native Method)
2012-09-08 18:38:38 [iNFO] [sTDERR] at sun.reflect.NativeMethodAccessorImpl.
invoke(Unknown Source)
2012-09-08 18:38:38 [iNFO] [sTDERR] at sun.reflect.DelegatingMethodAccessorI
mpl.invoke(Unknown Source)
2012-09-08 18:38:38 [iNFO] [sTDERR] at java.lang.reflect.Method.invoke(Unkno
wn Source)
2012-09-08 18:38:38 [iNFO] [sTDERR] at com.google.common.eventbus.EventHandl
er.handleEvent(EventHandler.java:69)
2012-09-08 18:38:38 [iNFO] [sTDERR] at com.google.common.eventbus.Synchroniz
edEventHandler.handleEvent(SynchronizedEventHandler.java:45)
2012-09-08 18:38:38 [iNFO] [sTDERR] at com.google.common.eventbus.EventBus.d
ispatch(EventBus.java:317)
2012-09-08 18:38:38 [iNFO] [sTDERR] at com.google.common.eventbus.EventBus.d
ispatchQueuedEvents(EventBus.java:300)
2012-09-08 18:38:38 [iNFO] [sTDERR] at com.google.common.eventbus.EventBus.p
ost(EventBus.java:268)
2012-09-08 18:38:38 [iNFO] [sTDERR] at cpw.mods.fml.common.LoadController.di
stributeStateMessage(LoadController.java:81)
2012-09-08 18:38:38 [iNFO] [sTDERR] at cpw.mods.fml.common.Loader.loadMods(L
oader.java:438)
2012-09-08 18:38:38 [iNFO] [sTDERR] at cpw.mods.fml.client.FMLClientHandler.
beginMinecraftLoading(FMLClientHandler.java:137)
2012-09-08 18:38:38 [iNFO] [sTDERR] at net.minecraft.client.Minecraft.a(Mine
craft.java:405)
2012-09-08 18:38:38 [iNFO] [sTDERR] at net.minecraft.client.Minecraft.run(Mi
necraft.java:737)
2012-09-08 18:38:38 [iNFO] [sTDERR] at java.lang.Thread.run(Unknown Source)
2012-09-08 18:38:38 [iNFO] [sTDERR] Caused by: java.lang.ClassNotFoundException:
Portal_TextureAnimation
2012-09-08 18:38:38 [iNFO] [sTDERR] at cpw.mods.fml.relauncher.RelaunchClass
Loader.findClass(RelaunchClassLoader.java:99)
2012-09-08 18:38:38 [iNFO] [sTDERR] at java.lang.ClassLoader.loadClass(Unkno
wn Source)
2012-09-08 18:38:38 [iNFO] [sTDERR] at java.lang.ClassLoader.loadClass(Unkno
wn Source)
2012-09-08 18:38:38 [iNFO] [sTDERR] ... 28 more
2012-09-08 18:38:38 [iNFO] [sTDERR] Caused by: java.lang.VerifyError: Cannot inh
erit from final class
2012-09-08 18:38:38 [iNFO] [sTDERR] at java.lang.ClassLoader.defineClass1(Na
tive Method)
2012-09-08 18:38:38 [iNFO] [sTDERR] at java.lang.ClassLoader.defineClass(Unk
nown Source)
2012-09-08 18:38:38 [iNFO] [sTDERR] at java.lang.ClassLoader.defineClass(Unk
nown Source)
2012-09-08 18:38:38 [iNFO] [sTDERR] at cpw.mods.fml.relauncher.RelaunchClass
Loader.findClass(RelaunchClassLoader.java:93)
2012-09-08 18:38:38 [iNFO] [sTDERR] ... 30 more