Javier,
In order to fix the problem it is necessary to replicate it. Have you been
using the snapshot version all along? If you install earlier versions of
gretl and/or gnuplot, does the problem persist? Does it happen only with
the particular series you sent in an earlier message, or does it happen
all the time?
Riccardo (Jack) Lucchetti
Dipartimento di Economia
Università Politecnica delle Marche
r.lucchetti(a)univpm.it
http://www.econ.univpm.it/lucchetti