What are these copied DVDs copies of? If they are commercially-sold movies or software, this is part of the copyright protection. May I suggest that you burn a DVD on another machine with some bootable free ISO image - maybe Parted Manager. Then put it in your drive and try to boot from it.
If it doesn't boot, you have a problem that we can work with. If it does, and only fails to read copied commercial DVDs, it's intended to work that way. The content providers can't trust us consumers not to rob them blind.