When squatting, even a really small amount of weight, as soon as I go anywhere near parallel I can feel my lower back start to "give". It's like my posture is about to collapse. I've had my form checked by people who squat well and heavy and they said it was fine so I'm ruling that out. I've also tried the crappy squat machine (which basically sets your form for you) and the same thing happens so I'm not really sure what to do. I can deadlift fine without any similar pain and the same goes for all the other back lifts. Any ideas what the problem is or how I can correct or strengthen it? Cliffs - lower back hurts when squatting, how to fix?