Try this. Have DVDNextCopy output to the hard drive rather than trying to burn with the program. Then try burning the dvd movie files with ImgBurn, which is a free burning program that we recommend highly.
Here is the guide for burning dvd video files to a disk using ImgBurn: http://forum.imgburn.com/index.php?showtopic=4632
(ImgBurn starts in Ez-Mode these days...to start it, click on Write files/folders to disc)
If this works, then you know there is something wrong with the software installation, and you might want to reinstall. Don't buy the software again by the way. I believe there are better choices for this process, like DVDFab.