OK, everyone. First, let me thank you for your time and apologize for wasting it.
I posted this because:
*The problem I described only happened with DVDs I made and not pre-recorded videos like a movie from Blockbuster.
*It was apparent when viewed in my DVD player and also a friends.
This led me to believe Roxio was the problem. I took a DVD to another friend to try and it worked fine. I have a Magnavox DVD player and so does my friend I originally tested with, although a different model. The person I just tried it with and had good results was using a Sony DVD player.
So, the bottom line is: Tomorrow, I will be purchasing a new DVD player and it will not be a Magnavox.
Once again, thank you for responding.