DVDs won't play in PC

Hi All,

My first post on Afterdawn and it's a plea for help. I have a couple of DVD movies that play fine on any stand alone DVD player, but won't play at all on the PC. When I insert the disc, it's simply not recognised. The disc spins, it *tries* to recognise it, but then just gives up. Result is the PC thinks there is no disc present. I have 3 PCs in the home, all have the same result. As I mentioned, these movies play fine in all standalone DVD players that I've tried. What can it be? I read on another forum something like some DVD movies have a code writen to the disc that prevents them from being read by PCs that have DVD copying software installed on them. Is this true? If so, how to get round it? What is interesting, is these probleatic DVD movies in question all share one thing in common - they are all "backups" from Malaysia (Johor). Could the authors of these backups have included something in the disc to prevent them from being played in a computer, in case they are, em, "backed-up" again?? I'm stumped. Any help appreciated!