iAm1nsaN3X

I found a semi-fix for this. I just downgraded Java 1.8.0_20 to Java 1.8.0_11. I found a post that was similar to mine and an admin replied that there's a bug with Java 1.8.0_20: Here's the link: http://www.oracle.com/technetwork/java/javase/downloads/java-archive-javase8-2177648.html#jre-8u11-oth-JPR

Oct 13, 2014 1:12:51 PM net.minecraft.launchwrapper.LogWrapper log INFO: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker Oct 13, 2014 1:12:52 PM net.minecraft.launchwrapper.LogWrapper log INFO: Using primary tweak class name cpw.mods.fml.common.launcher.FMLTweaker Oct 13, 2014 1:12:52 PM net.minecraft.launchwrapper.LogWrapper log INFO: Calling tweak class cpw.mods.fml.common.launcher.FMLTweaker 2014-10-13 13:12:52 [iNFO] [ForgeModLoader] Forge Mod Loader version 6.4.49.965 for Minecraft 1.6.4 loading 2014-10-13 13:12:52 [iNFO] [ForgeModLoader] Java is Java HotSpot 64-Bit Server VM, version 1.8.0_20, running on Windows 7:amd64:6.1, installed at C:\Program Files\Java\jre1.8.0_20 2014-10-13 13:12:52 [iNFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker 2014-10-13 13:12:52 [iNFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker 2014-10-13 13:12:52 [iNFO] [ForgeModLoader] Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker 2014-10-13 13:12:52 [sEVERE] [ForgeModLoader] Unable to launch java.util.ConcurrentModificationException at java.util.ArrayList$Itr.checkForComodification(Unknown Source) at java.util.ArrayList$Itr.remove(Unknown Source) at net.minecraft.launchwrapper.Launch.launch(Launch.java:114) at net.minecraft.launchwrapper.Launch.main(Launch.java:27) Picked up _JAVA_OPTIONS: -Djava.net.preferIPv4Stack=true Java HotSpot 64-Bit Server VM warning: Using incremental CMS is deprecated and will likely be removed in a future release ---- This keeps on happening for every mod pack I run with even other versions of forge, I have looked for fixes on Google but it seems like not many people know how to answer this problem...