  In this comment we point out several problems concerning kinematical
singularities which are encountered in the calculation of the dilepton rates in
{Ruppert:2004yg}. We also comment on the method introduced in {vanHees:2000bp}
and further used in refs. {Riek:2004kx,Renk:2006dt,Renk:2006ax,Ruppert:2004yg}
