  Motivated by a recent discussion about the role of flat directions, a typical
feature of supersymmetric models, in the process of particle production in the
early universe a consistent model of inflation and preheating in supergravity
with MSSM fields has been built. It is based on a model proposed by M.
Kawasaki, M. Yamaguchi and T. Yanagida. In the inflationary stage, the flat
directions acquire large vacuum expectation values (VEVs) without spoiling the
background of slow-roll, high-scale inflation consistent with the latest WMAP5
observational data. In the stage of particle production, naturally following
inflation, the role of flat direction large VEVs depends strongly on effects
connected with the supergravity framework and non-renormalizable terms in the
superpotential, which have been neglected so far in the literature. Such
effects turn out to be very important, changing the previous picture of
preheating in the presence of large flat direction VEVs by allowing for
efficient preheating from the inflaton.
