"Because" I have a DVD data disc that none of the Macs I have with DVD readers.. can read. and wanted to verify my thoughts.. that it was possibly a DVD disc that was burned that I just won't be able to read on Macintosh. Or if maybe there was some other reason, I was unaware of. You still haven't said what is supposed to be on the disk. At a hardware level, there are minor incompatabilities among drives and media: you just may have a combination that doesn't work. In this case, it might not work on other Windows machines with different DVD drives. Craig