  Spin tunneling in molecular magnets controlled by dipole-dipole interactions
(DDI) in the disordered state has been considered numerically on the basis of
the microscopic model using the quantum mean-field approximation. In the actual
case of a strong DDI spin coherence is completely lost and there is a slow
relaxation of magnetization, described by t^{3/4} at short times. Fast
precessing nuclear spins, included in the model microscopically, only
moderately speed up the relaxation.
