  Using density matrix equations of motion and a tight-binding band
calculation, we predict all-optical switching between four metastable magnetic
states of (III,Mn)As ferromagnets. This switching is initiated non-thermally
within 100fs, during nonlinear coherent photoexcitation. For a single optical
pulse, magnetization reversal is completed after $\sim$100 ps and controlled by
the coherent femtosecond photoexcitation. Our predicted switching comes from
magnetic nonlinearities triggered by a femtosecond magnetization tilt that is
sensitive to un--adiabatic light--induced spin interactions.
