lembas,
I realized later that I misunderstood a possible relation of the bug I had
with the description of the bug you linked to, after I quickly read it, when
you posted the link to the description here. And, therefore, ended up not
trying to implement that particular solution.
The problem I had was just that it took too long to reboot or shut down. I
never experienced any kind of freeze. And I could reboot with no problems. So
it was not the same bug.
Anyway, I decided to wait for the next release of Trisquel and also to
install another very similar Ubuntu-based distro on that particular computer,
so that I can make a comparison later, in terms of performance, when I
install Trisquel again.
Thank you very much for your help.