I'm trying to add some mods in 1.6.4 and it keeps saying this please help
Nov 11, 2014 3:12:13 PM net.minecraft.launchwrapper.LogWrapper log
INFO: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker
Nov 11, 2014 3:12:14 PM net.minecraft.launchwrapper.LogWrapper log
INFO: Using primary tweak class name cpw.mods.fml.common.launcher.FMLTweaker
Nov 11, 2014 3:12:14 PM net.minecraft.launchwrapper.LogWrapper log
INFO: Calling tweak class cpw.mods.fml.common.launcher.FMLTweaker
2014-11-11 15:12:14 [INFO] [ForgeModLoader] Forge Mod Loader version 6.4.49.965 for Minecraft 1.6.4 loading
2014-11-11 15:12:14 [INFO] [ForgeModLoader] Java is Java HotSpot(TM) 64-Bit Server VM, version 1.8.0_25, running on Windows 8.1:amd64:6.3, installed at C:\Program Files\Java\jre1.8.0_25
2014-11-11 15:12:14 [INFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
2014-11-11 15:12:14 [INFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker
2014-11-11 15:12:14 [INFO] [ForgeModLoader] Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
2014-11-11 15:12:14 [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(TM) 64-Bit Server VM warning: Using incremental CMS is deprecated and will likely be removed in a future release
Nov 11, 2014 3:12:13 PM net.minecraft.launchwrapper.LogWrapper log
INFO: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker
Nov 11, 2014 3:12:14 PM net.minecraft.launchwrapper.LogWrapper log
INFO: Using primary tweak class name cpw.mods.fml.common.launcher.FMLTweaker
Nov 11, 2014 3:12:14 PM net.minecraft.launchwrapper.LogWrapper log
INFO: Calling tweak class cpw.mods.fml.common.launcher.FMLTweaker
2014-11-11 15:12:14 [INFO] [ForgeModLoader] Forge Mod Loader version 6.4.49.965 for Minecraft 1.6.4 loading
2014-11-11 15:12:14 [INFO] [ForgeModLoader] Java is Java HotSpot(TM) 64-Bit Server VM, version 1.8.0_25, running on Windows 8.1:amd64:6.3, installed at C:\Program Files\Java\jre1.8.0_25
2014-11-11 15:12:14 [INFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
2014-11-11 15:12:14 [INFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker
2014-11-11 15:12:14 [INFO] [ForgeModLoader] Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
2014-11-11 15:12:14 [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(TM) 64-Bit Server VM warning: Using incremental CMS is deprecated and will likely be removed in a future release
Solution: Download this and place it in your mods folder.