Disabled Lightning Recode, as suggested, and the backup copy now plays perfectly. Guess that was the next logical step to try.
One caveat. I usually only backup the main movie with English DTS audio and any English subtitle tracks. I had those options on the first copy - the one that "shuddered." On this second attempt backing up, when I did first copy (without compression) to the hard drive with those English only options, DVDFab wouldn't stop "scanning" - got to 96%, went to 99%, then back to 96%, back to 99%, and so on. So I bailed on that attempt, and the next try I copied the main movie and all audio plus subtitle options - so DVDFab didn't have to do any "scanning" at all. Don't know if that was the original problem or not.
I'm pragmatic - don't care how it works as long as it works. So thanks for your help, and I've learned a little bit more about DVDFab Blu-ray copy. :)
