Okay, so I was trying to open my bteam for the first and here's the error:
[B#439] 2014-11-21 19:52:38 [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(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=128m; support was removed in 8.0
