I doubt he has a multi-system DVD player. Your burner could have the wrong region code, your DVD authoring program could be set for the wrong region, or you could have something like AnyDVD set for the wrong region. If you live in North America, it should be NTSC, PAL is for Europe. There are some others and some variations of these, but these are the ones most countries use. Check these out and tell us what you see.
well I wouldn't think so, but it's always a possibility. You could try burning it for the region you are in, I have never had a region free disc not work, but maybe your player is buggy and only plays ones designated for a specific region.