Minecraft wont launch ANY forge type profiles/versions

[emergedchafff1]

My Minecraft wont launch forge i cant figure out why pleAug 23, 2014 2:33:35 PM net.minecraft.launchwrapper.LogWrapper log

INFO: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker

Aug 23, 2014 2:33:36 PM net.minecraft.launchwrapper.LogWrapper log

INFO: Using primary tweak class name cpw.mods.fml.common.launcher.FMLTweaker

Aug 23, 2014 2:33:36 PM net.minecraft.launchwrapper.LogWrapper log

INFO: Calling tweak class cpw.mods.fml.common.launcher.FMLTweaker

2014-08-23 14:33:36 [iNFO] [ForgeModLoader] Forge Mod Loader version 6.4.49.965 for Minecraft 1.6.4 loading

2014-08-23 14:33:36 [iNFO] [ForgeModLoader] Java is Java HotSpot 64-Bit Server VM, version 1.8.0_20, running on Windows 8.1:amd64:6.3, installed at C:\Program Files\Java\jre1.8.0_20

2014-08-23 14:33:36 [iNFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker

2014-08-23 14:33:36 [iNFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker

2014-08-23 14:33:36 [iNFO] [ForgeModLoader] Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker

2014-08-23 14:33:36 [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)

Java HotSpot 64-Bit Server VM warning: Using incremental CMS is deprecated and will likely be removed in a future release

ase help heres the launch code

[LexManos]

Use java 7 or earlier versions of java 8, update 20 introduced some odd changes to the concurrency support in lists.