I am actually having the same problem as well...
so with me i have to use the .jar file in order to even get to the main mod menus, after selecting the mod it starts to download and freezes usually after a couple of seconds, now i have tried disabling AVG, installing java (64bit, 32, or both) and still nothing same result.
deleting the files in %appdata% doesnt help, clearing the cache does nothing for me either, all my drivers are up to date including java.
is there anything else i can do to make this work? manual instal of the mods or a different launcher version? i am running out of ideas and forum/google searches
anything at all will be a welcomed help