To date we have not had a comeback where the DVD did not work at all. In the two cases we had both turned out to be menu settings on the DVD player rather than an incompatible disc. The only areas that have caused some problems are laptop / notebook pc’s. This is usually sorted out by downloading a free media player like VLC Player. Not all laptops (especially the older ones) have the correct codec’s installed for DVD playback. All DVD’s mastered by us are tested on “off the shelf” DVD players. Most, if not all late model DVD players are compatible with DVD-R formats and will play PAL and NTSC DVD’s. We consider a DVD to be a working DVD if it plays in any of our playback devices.