As far as I can tell it ONLY crashes when I use PureBDcraft vanilla texture pack and their hud texture. I've tried the same world with purebdcraft, zigzag and the default texture pack. It has crashed around 10 times in the last 2 days. I have no idea what's going on. 

EDIT: Nevermind it just took longer. Seems it doesn't crash for default texture pack. I played with default for more than an hour and it was fine.