I can only repeat what nmsalgueiro and others are saying. The discs are fine, despite the error message and checking the checksum in terminal confirms this.
-- Error while burning - some files may be corrupted on the disc https://bugs.launchpad.net/bugs/367037 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs