The problem is, simply, as follows
After having bricked MBW (newb at linux, probably entered a bad command in the star-up list) and unbricked it using the rescue procedure, everything works like a charm
BUT, probably something has gone badly wrong with the partitions, as since the unbricking, the darn thing uses for some reason the 3gb partition to store data, instead of the 460Gb one.
Is there a way to fix that without having to redo the whole procedure again?
(And even then I am not sure it will be fixed, as I don't know what went wrong). :-/