The currently (2010) widely accepted/believed description of the birth and evolution of the universe and of its contents is "Lambda Cold Dark Matter Concordance Cosmological Model" (LCDM CCM) … My own research was very much confined to the early version of the LCDM CCM (mid-1990's) when I began performing numerical experiments on the satellite galaxies of the Milky Way. I was quite happy with the CCM, as everyone else, and did not bother with the fundamental issues raised by some. With time, however, it became apparent that the LCDM CCM accounts poorly for the properties of the satellite galaxies and their distribution about the Milky Way. Warm dark matter models fared no better.

Pavel Kroupa: Dark Matter, Cosmology and Progress website (July 4, 2010).