Alignment won't cause crab walk, something is out of square. Check to make sure the spring pins are in the holes, or anything else that would cause unequal measurments between the front and rear tires. Measure from front hub to rear hub on both sides, are they the same? If not, find out why. If yes, then measure diagonal (not easy) front to opposite right. that checks for "diamonding" which can result from a warped frame among other things...