You might want to consider seeing a chiropractor or what are they called (treilin probably knows) a sports medicine physiologist? A body mechanics person. If you have weakness/tightness somewhere something's goofy someplace else.
Okay, one more thing to think about: What kind of shoes are you wearing? I can't squat ATF even with no weight with the wrong shoes on, I've got my "deadlifting shoes" I use -- can't walk a quarter mile in the suckers, but perfect for weights.
Okay, one more thing to think about: What kind of shoes are you wearing? I can't squat ATF even with no weight with the wrong shoes on, I've got my "deadlifting shoes" I use -- can't walk a quarter mile in the suckers, but perfect for weights.