Excuses to the list, this problem is a "peculiarity" of my system that I (thought) had solved, but after installing a (non-R) package seems to be here again. Agus Dr. Agustin Lobo Instituto de Ciencias de la Tierra (CSIC) Lluis Sole Sabaris s/n 08028 Barcelona SPAIN tel 34 93409 5410 fax 34 93411 0012 alobo at ija.csic.es