After installing IC2 1.108.71 and running Minecraft, I simply get a black screen after the Mojang logo, and this appears in my ForgeModLoader-client-0.log:
EDIT: Using Minecraft 1.4.4, Forge 6.3.0.372, and IC2 version posted above.
2012-11-18 03:58:47 [FINER] [ForgeModLoader] Sending event FMLConstructionEvent to mod IC2
2012-11-18 03:58:47 [INFO] [STDERR] java.lang.ClassNotFoundException: ic2.common.ItemIC2
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.relauncher.RelaunchClassLoader.findClass(RelaunchClassLoader.java:141)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.ClassLoader.loadClass(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.ClassLoader.loadClass(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at net.minecraftforge.transformers.EventTransformer.buildEvents(EventTransformer.java:54)
2012-11-18 03:58:47 [INFO] [STDERR] at net.minecraftforge.transformers.EventTransformer.transform(EventTransformer.java:35)
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.relauncher.RelaunchClassLoader.runTransformers(RelaunchClassLoader.java:178)
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.relauncher.RelaunchClassLoader.findClass(RelaunchClassLoader.java:133)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.ClassLoader.loadClass(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.ClassLoader.loadClass(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.Class.forName0(Native Method)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.Class.forName(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.common.FMLModContainer.constructMod(FMLModContainer.java:410)
2012-11-18 03:58:47 [INFO] [STDERR] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
2012-11-18 03:58:47 [INFO] [STDERR] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.reflect.Method.invoke(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:69)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.EventBus.dispatch(EventBus.java:317)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:300)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.EventBus.post(EventBus.java:268)
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:140)
2012-11-18 03:58:47 [INFO] [STDERR] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
2012-11-18 03:58:47 [INFO] [STDERR] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.reflect.Method.invoke(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:69)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.EventBus.dispatch(EventBus.java:317)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:300)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.EventBus.post(EventBus.java:268)
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.common.LoadController.distributeStateMessage(LoadController.java:83)
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.common.Loader.loadMods(Loader.java:478)
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:150)
2012-11-18 03:58:47 [INFO] [STDERR] at net.minecraft.client.Minecraft.a(Minecraft.java:424)
2012-11-18 03:58:47 [INFO] [STDERR] at net.minecraft.client.Minecraft.run(Minecraft.java:756)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.Thread.run(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] Caused by: java.lang.VerifyError: Cannot inherit from final class
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.ClassLoader.defineClass1(Native Method)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.ClassLoader.defineClass(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.ClassLoader.defineClass(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.relauncher.RelaunchClassLoader.findClass(RelaunchClassLoader.java:134)
2012-11-18 03:58:47 [INFO] [STDERR] ... 36 more
2012-11-18 03:58:47 [INFO] [STDERR] Exception in thread "Minecraft main thread" java.lang.NoClassDefFoundError: ic2/common/ItemDebug
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.Class.forName0(Native Method)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.Class.forName(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.common.FMLModContainer.constructMod(FMLModContainer.java:410)
2012-11-18 03:58:47 [INFO] [STDERR] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
2012-11-18 03:58:47 [INFO] [STDERR] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.reflect.Method.invoke(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:69)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.EventBus.dispatch(EventBus.java:317)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:300)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.EventBus.post(EventBus.java:268)
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:140)
2012-11-18 03:58:47 [INFO] [STDERR] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
2012-11-18 03:58:47 [INFO] [STDERR] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.reflect.Method.invoke(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:69)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.EventBus.dispatch(EventBus.java:317)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:300)
2012-11-18 03:58:47 [INFO] [STDERR] at com.google.common.eventbus.EventBus.post(EventBus.java:268)
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.common.LoadController.distributeStateMessage(LoadController.java:83)
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.common.Loader.loadMods(Loader.java:478)
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:150)
2012-11-18 03:58:47 [INFO] [STDERR] at net.minecraft.client.Minecraft.a(Minecraft.java:424)
2012-11-18 03:58:47 [INFO] [STDERR] at net.minecraft.client.Minecraft.run(Minecraft.java:756)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.Thread.run(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] Caused by: java.lang.ClassNotFoundException: ic2.common.ItemDebug
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.relauncher.RelaunchClassLoader.findClass(RelaunchClassLoader.java:141)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.ClassLoader.loadClass(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.ClassLoader.loadClass(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] ... 28 more
2012-11-18 03:58:47 [INFO] [STDERR] Caused by: java.lang.NoClassDefFoundError: ic2/common/ItemIC2
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.ClassLoader.defineClass1(Native Method)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.ClassLoader.defineClass(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.ClassLoader.defineClass(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.relauncher.RelaunchClassLoader.findClass(RelaunchClassLoader.java:134)
2012-11-18 03:58:47 [INFO] [STDERR] ... 30 more
2012-11-18 03:58:47 [INFO] [STDERR] Caused by: java.lang.ClassNotFoundException: ic2.common.ItemIC2
2012-11-18 03:58:47 [INFO] [STDERR] at cpw.mods.fml.relauncher.RelaunchClassLoader.findClass(RelaunchClassLoader.java:76)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.ClassLoader.loadClass(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] at java.lang.ClassLoader.loadClass(Unknown Source)
2012-11-18 03:58:47 [INFO] [STDERR] ... 34 more
I'm certain Forge was installed correctly, as NEI works just fine. I simply installed the IC2 jar to the mods folder, just like every other modpack. So I don't quite understand why Minecraft cannot find the mod's folders if it's supposed to be looking in the mods folder in the first place.
Thanks for your time. I hope I don't have to actually put the mod in the minecraft.jar. I've personally never heard of anyone needing to do that with IC2 (or any other mod).