Molecular simulations are carried out to test whether the disordered packing configurations that are stable in soft potential systems are also stable in hard potential systems, and vice versa. To carry out this test, the properties of packing configurations corresponding to energy minima are examined as the steepness of the interparticle potential changes. A normal mode analysis shows that as the steepness of the potential changes, energy minima flatten out and disappear. Thus packing configurations that are stable for a soft potential system are not stable for hard potential systems, and vice versa. This result for disordered particle packing configurations contrasts with the result for the ordered packing configurations that underlie crystals, in which the same packing configurations are stable in both soft and hard potential systems. (C) 2003 American Institute of Physics.