Copying with Nero and 80 minute CDs

My friend brought over 30 Dreamcast games to copy. They already been copied from images onto CD (not sure which proggy).
I copied a few of them onto my 80 minute CDs using Nero 5 and tried to use them.. No luck at all, not even when trying to use Nero boot disc or any other boot disc, heh.

If anyone has experience in this problem or knows how to fix it, please reply back to help me play my new games.