  New simulations are presented which investigate the formation of smaller
groups of galaxies in a CDM like universe. The simulations follow the evolution
of dark matter and gas and are performed with an SPH code adapted for the
special-purpose hardware GRAPE. The mass resolution in the baryonic component
is 5 10^6 Msol, the spatial resolution is 1.5 kpc. A sufficiently large volume
is simulated in order to accurately include the tidal field and the mass
inflow. The mass resolution enables us to resolve the galaxies formed in the
simulation. Individual properties of the galaxies, each consisting of several
thousand particles, can also be investigated.
  It turns out, that in the center of the dark haloes the gas accumulates to
form a rotationally supported disk. However, in comparison with observations,
disks which form in numerical simulations are too concentrated: Due to the
merging of substructures, angular momentum is transported from the gas to the
dark halo, and far too much gas is accumulated at very small radii. It is
argued that changing the cosmogony (e.g. to low Omega) or adding
photoionisation due to an external UV background do not provide an easy fix to
the angular momentum problem. Feedback processes caused by supernovae or
stellar winds seem to be the most likely solution to this problem.
