The authors have carried out Monte Carlo simulations of a system of classical three-dimensional spins interacting with their nearest neighbours in a FCC lattice. Spins randomly occupy one half of the lattice sites and interact via antiferromagnetic Heisenberg exchange as well as via quenched, random Dzyaloshinskii-Moriya (DM) anisotropy. They calculate the relaxation times ( tau ) against temperature (T) in the range 0.25<or=kT/J<or=2.0 for systems of 4L3 sites with L=4, 6 and 8, and for various values of the strength of DM anisotropy (D): D=0.01, 0.3 and 0.5. The expression tau =exp(A/(T - T0)y) fits the data rather well in all cases, A is about 0.015 and is independent of L, D and T, y varies slightly between 1.25 for D=0 and 1.45 for D=0.5, T0 is below 0.1 J/k and the best fit to our data indicates that TO=0. They conclude that no phase transition exists when one half of the lattice sites are occupied by spins, and also that the effect of DM anisotropy is only to shift slightly the value of the exponent y in the expression of tau (T).