Well Simon, thanks for the information.
But I just was with Sandra on messenger, and found that this problem seems to happen not only to me. There are many others with other burners and other DVD brand and other burning programs, having the same problem, and not yet a satisfying answer for that mystery.
Lovely Sandra will continue searching for the answer, and so me too.
If some others like to participate in searching or in suggestions, their help will be appreciated.
Thanks in advance...