  We present the Curci-Ferrari model on the lattice. In the massless case the
topological interpretation of this model with its double BRST symmetry relates
to the Neuberger 0/0 problem which we extend to include the ghost/anti-ghost
symmetric formulation of the non-linear covariant Curci-Ferrari gauges on the
lattice. The introduction of a Curci-Ferrari mass term, however, serves to
regulate the 0/0 indeterminate form of physical observables observed by
Neuberger. While such a mass m decontracts the double BRST/anti-BRST algebra,
which is well-known to result in a loss of unitarity, observables can be
meaningfully defined in the limit m to 0 via l'Hospital's rule. At finite m the
topological nature of the partition function used as the gauge fixing device
seems lost. We discuss the gauge parameter xi and mass m dependence of the
model and show how both cancel when m = m(xi) is appropriately adjusted with
xi.
