I found this difference between "hts-log.txt" and "View log file" from inside
HTTrack:

From "hts-log.txt":
Error:  "Not Found" (404) at link www.___.it/impurità%20nel___.htm

From "View log file" inside HTTrack:
Error:  "Not Found" (404) at link www.___.it/impurità%20nel___.htm

"à" become "Ã" plus a space.

The name of the empty (Error 404 - File or directory not found) file
downloaded is:
"impurità nel___.htm" (with two space between "Ã" and "n").

Of course the page is available with the correct link (with the "à").

I tried to search in the forum and I found similar problems but no solution
("swedish characters in image names" and "Danish special charaters in html
filename goes bad")

I am using HTTrack3.44-1 with Windows XP SP3.

Thanks for any suggestions.