Hello !
I had the same problem with 1.6.4 version, and I've fixed it by installing this mod in the mod folder: http://files.minecraftforge.net/LegacyJavaFixer/legacyjavafixer-1.0.jar
try to delete any other mods in this folder the first time your run the game with LegacyJavaFixer
Normaly the game will launch !