1.7.4+ Crashes Upon Load

Hi! a few months ago i made a post explaning my problem. they told me to go to the Mojang support website but they just told me to come here. my problem is that whenever i load 1.7.4 or any new snapshots that came after 1.7.4 my game just crashes. now i dont know whats happening but i can olny play 1.7.2 and anything under that