The wise men and ladies of the forum are out for the moment, so you’ll have to make do with me until they arrive.
Yours is an unusual problem. What we normally see are DVD’s that don’t play on stand alone players, but do play on the computer.
Issues with DVD playback usually come down to one of three problems. Poor media, that is hard to read once burned. Hardware that doesn’t read burned discs very well. Or poorly authored DVD-video, that doesn’t quite meet the specifications of the format.
So, I have a few questions. How did you make the DVD-videos that will not play on the computer drive? Are these home-made videos that you have converted/authored into DVD-video? Or are these copies of commercial DVD’s that you own?
What type of blank discs are you using and what is the make and model of your burner? Some drives are known to be relatively poor readers.
Have you tried other software to play the DVD’s? VLC or Media Player Classic Home Cinema are two free players that can play DVD-video. If they do not work, try examining the disc with ISOBuster (free version) and see if any type of software can find and examine the contents of the discs.
Oh, and welcome to the forums GML.