BuzzPCSOS the risk of being called mean I must ask, have you tried playing a commercial DVD in it? Just to make sure that the fault really is with the burnt discs.
Nothing mean about it. I did watch a couple commercial DVDs right after I bought it (Bull Durham and something else) and just doublechecked again just so I could answer your question.
Switching brands worked although I can't prove it.
Also a factor that is maybe Lenovo, 13 years ago, but in a bottom-of-the-barrel optic drive. I think that could be very well.
You and 007 both mentioned the quality/encoding of any mp4 movie I've collected is a huge factor and 007 above said the movie output I showed him proved I had burn-unworthy mp4...which means it would never open anyway after burn.
You both also told me what Handbrake could do re: proper encoding. It would break my heart to use yet another program to get the DVD movie mp4 "worthy" so it could be used in another program to burn to disk.
Who the hell woulda thought burning an mp4 movie to DVD would be such a hassle? It wasn't when I was younger and I don't think I'm getting stupider, per se, maybe standards across the board were more uniform? Who knows π.
So...variables:
old lenovo optic drive
el cheapo DVD player
not--worthy-to-burn-to-a-disk collection of mp4 movies...
I have to educate myself and learn to declare my collection crappy and needs fixin I guess. I really need to learn what 'not worthy' is by learining how to read my own output then I can learn how to make Handbrake (I'm good in Handbrake) make it 'worthy' for burning.
Once it becomes 'worthy' to be burned maybe the Verbatims and balance of DVD burners that fail me might actually work.
SIGH π
EDIT: I like your 7-step program better