Some dvds flag unexpected format...womt play?

most of these prob dvds afe mail ord. or downloaded om my
windoe xp home..... have several plyrs ...(real, cyberlink, Wind med. plyr....all respond same to these discs..... are they just
data I need to burn to video or do I need a codec (adp) to
fix problem thank you much alan
addd:lijet22222000@yahoo.com