The most common cause is insanely low node capacitances.
Elements which are bistable or singular also play hell. Try
looking at the diode in isolation if you are convinced it's the
problem and not the victim, especially for signs of an I-V
"blowup", junction capacitance approaching zero or worse
yet changing sign, etc.
Ehat this error mesage purports is that your last timestep
had some error, that no amount of downranging timestep
can pull in - because the error is already embedded to the
matrix.
This being the case you might look at the final timepoint
for unreasonable voltages / currents, and figure out who
is pushing garbage.