[Can't launch MC. I need help.]

I am trying to load a modpack and when I click play it scrolls through the norms but then I get this message in the console:

 

[b#439]  2014-11-05 16:26:44 [iNFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker

[b#439]  2014-11-05 16:26:44 [iNFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker

[b#439]  2014-11-05 16:26:44 [iNFO] [ForgeModLoader] Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker

[b#439]  2014-11-05 16:26:44 [sEVERE] [ForgeModLoader] Unable to launch

[b#439]  java.util.ConcurrentModificationException

[b#439]   at java.util.ArrayList$Itr.checkForComodification(Unknown Source)

[b#439]   at java.util.ArrayList$Itr.remove(Unknown Source)

[b#439]   at net.minecraft.launchwrapper.Launch.launch(Launch.java:114)

[b#439]   at net.minecraft.launchwrapper.Launch.main(Launch.java:27)

[b#439]  Java HotSpot Client VM warning: ignoring option MaxPermSize=128m; support was removed in 8.0

 

Can anybody help me?