We report on molecular dynamics simulation of long-time tails in the v
elocity and stress autocorrelation functions of a dense two-dimensiona
l fluid. Large systems of the order of hundred thousand particles have
been investigated, performing canonical averages over an ensemble of
trajectories generated on a parallel computer. We find the well-known
t(-1) decay for the velocity autocorrelation function at two different
densities of the;fluid, together with a faster than linear time depen
dence for the mean-square displacement at long times. Although there a
re indications of an asymptotically faster decay, the data are not pre
cise enough to discriminate whether the decay is in agreement with the
(t root 1n t)(-1) prediction of consistent mode-coupling theory or it
is due to finite size effects. No evidence, within the statistical er
rors, is found for a long-time tail in the stress autocorrelation func
tion. This finding is in agreement with recent NEMD results [Hoover et
al., Phys. Rev. E 51 (1995) 273; Gravina et al., Phys. Rev. E 52 (199
5) 6123], who find an analytical dependence of the shear viscosity upo
n the shear rate with no evidence for divergence in the Green-Kubo val
ue.