  We develop a multi order parameter mean-field formalism for systems of
coupled quantum rotors. The scheme is developed to account for systems where
{\it ortho-para} distinction is valid. We apply our formalism to solid H$_2$
and D$_2$. We find an anomalous {\it reentrant} orientational phase transition
for both systems at thermal equilibrium. The correlation functions of the order
parameter indicate short-range order at low temperatures. As temperature is
increased the correlation increases along the phase boundary. We also find that
even extremely small {\it odd-J} concentrations (1%) can trigger short-range
orientational ordering.
