Maybe the Roxio forum would be a better place to look for an answer. The “usual suspects” don’t appear to be the problem. You have used the program for slideshows and other video projects using, as your source, your newer digital camera. So, your burner isn’t the problem, the brand of blank disk doesn’t seem to be the problem, and Roxio doesn’t seem to be the problem. I can’t imagine why importing from your Panasonic would be any different than importing from your digital camera. Just a long shot, try burning the project to a different brand of DVD, Verbatim or TY are the preferred media.
I was hoping someone who uses this Roxio program would post, but it doesn’t look like it.
Sorry and good luck.