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ive downloaded and used minecraft forge 1.6.4 before and never had problems, but i got a new computer and wa trying to install minecraft forge 1.6.4 and it wont open, when i set it to keep launcher open i got this message

Oct 25, 2014 5:16:07 PM net.minecraft.launchwrapper.LogWrapper log
INFO: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker
Oct 25, 2014 5:16:08 PM net.minecraft.launchwrapper.LogWrapper log
INFO: Using primary tweak class name cpw.mods.fml.common.launcher.FMLTweaker
Oct 25, 2014 5:16:08 PM net.minecraft.launchwrapper.LogWrapper log
INFO: Calling tweak class cpw.mods.fml.common.launcher.FMLTweaker
2014-10-25 17:16:09 [INFO] [ForgeModLoader] Forge Mod Loader version 6.4.49.965 for Minecraft 1.6.4 loading
2014-10-25 17:16:09 [INFO] [ForgeModLoader] Java is Java HotSpot(TM) Client VM, version 1.8.0_25, running on Windows 8.1:x86:6.3, installed at C:\Program Files (x86)\Java\jre1.8.0_25
2014-10-25 17:16:10 [INFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
2014-10-25 17:16:10 [INFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker
2014-10-25 17:16:10 [INFO] [ForgeModLoader] Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
2014-10-25 17:16:10 [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) Client VM warning: Using incremental CMS is deprecated and will likely be removed in a future release



if you know hoow to fix this please help