Thanks Marc,
yes -- you live, you learn, as they say. Unfortunately, I was not able to use the existing mpeg file to burn a dvd from a new project. It rendered for a hour, and then started to compile disc, and suddenly gave me the same annoying message that the source files are not valid.
Anyway, the happy end: I re-captured all the original footage and re-did the whole thing from scratch. Went home at 3 am, happy.
Now our Embassy has the post video, and my pride is saved
inna
p.s. That was my first experience working with Pinnacle studio. I've read a lot of negative reviews about it before I undertook this project. I was a little nervous, but could not choose here - I had to work with what I got from our IT department.
I should say that although not so robust as Adobe Premiere Pro (and not so complicated too), Pinnacle is a good software for amature video production... especially when you know exactly what you are doing!