[onemanguitarband]

I'm not really sure why it is having trouble with your computer play back. But I wonder about your standalone player. Have you used any DVD+/-R burned by other people in it? The particular model you have seems to have some terrible reviews.

I have a Samsung Upconverting DVD player (their top of the line player) and it is great in many regards, but can be quite picky about the burner used to create the disc (even using the best quality media). In fact you can use crappy media as long as you use an HP 630i burner.

The playback problem on the computer is puzzling, if you haven't played back DVD+/-Rs before, you might want to see if you can get your hands on some that were burned by someone else, to narrow down the problem.