  We discuss the regularity of solutions of 2D incompressible Navier-Stokes
equations forced by singular forces. The problem is motivated by the study of
complex fluids modeled by the Navier-Stokes equations coupled to a nonlinear
Fokker-Planck equation describing microscopic corpora embedded in the fluid.
This leads naturally to bounded added stress and hence to $W^{-1,\infty}$
forcing of the Navier-Stokes equations.
