If your dvd will play on your computer but will not play on your set-top player then there's a few possible reasons. One is the media you used. Depending on your set-top dvd player, some won't play some brands of disks, some won't play dvd+, some won't play those that are burnt too fast, some won't play RW disks, some won't even play home-made disks dvd-/+R.

If the disk doesn't play in your computer either then the cause may be with the way you burnt it. Also is your dvd player set up to play PAL, NTSC, SECAM? Some movies you might get a hold of might not be in the same colour format. Depending on where you live some dvd players will play both either by auto detecting the format or you may be required to switch the player over to another format.