  We address the interesting temperature range of a glass forming system where
the mechanical properties are intermediate between those of a liquid and a
solid. We employ an efficient Monte-Carlo method to calculate the elastic
moduli, and show that in this range of temperatures the moduli are finite for
short times and vanish for long times, where `short' and `long' depend on the
temperature. By invoking some exact results from statistical mechanics we offer
an alternative method to compute shear moduli using Molecular Dynamics
simulations, and compare those to the Monte-Carlo method. The final conclusion
is that these systems are not "viscous fluids" in the usual sense, as their
actual time-dependence concatenates solid-like materials with varying local
shear moduli.
