  Statistics of many particle energy levels of a finite two-dimensional system
of interacting electrons is numerically studied. It is shown that the
statistics of these levels undergoes a Poisson to Wigner crossover as the
strength of the disorder is decreased. This transition occurs at a similar
strength of disorder as the one-electron delocalization crossover in a finite
2d system and develops almost simultaneously at all energies. We interpret this
crossover in terms of delocalization in the space of occupation numbers of
strongly bound and compact electron-hole pairs (excitons).
