The way it's been explained to me is that the reflectivity on a home recorded CD-R cannot be read by the laser on some machines. It has something to do with the sensitivity of either the CD surface, the laser, or both. I recently bought a DVD player at Best Buy---a Panasonic, model 32 (I think). It cost a little over a hundred bucks and plays everything. I took one of my CD-Rs with me and tried them on each machine on the shelf. On most, the screen would read "no disk". The Panasonic worked fine and has played everything I've thrown at it.