Numerical Evaluation of One-Loop Diagrams Near Exceptional Momentum   Configurations
  One problem which plagues the numerical evaluation of one-loop Feynman diagrams using recursive integration by part relations is a numerical instability near exceptional momentum configurations. In this contribution we will discuss a generic solution to this problem. As an example we consider the case of forward light-by-light scattering. 
W. Giele, E.W.N. Glover and G. Zanderighi