Check very carefully that the ARC info DGL files have the east and north
coords in the right order and that the full values are there (some arc/info
dlg formats put out a modified northing (near the equator) and then when
you import them everything works fine, but no display.
Another check you can make is to set
g.region vect=mapname
d.erase
d.vect mapname
where mapname is one of the GRASS maps you have built from DLG. Also,
look at the file sizes in dig and dig_att to see if they make sense.
Jim Hinthorne