front discs locking up

more info is needed to help. Are calipers free, do you have a power booster, does car have headers near brake lines, how much drag on the rotors before you take a ride ? This is an easy problem if you get all things are checked. make sure brake fluid is not contaminated. one strange problem can be the rubber line have an implosion (that means the fluid goes to the wheel from pedal pressure by your foot and it can't return at normal flow) this is a problem when the lines are ancient. Good Luck