Those Sparcs are a pain to get booting on CD. I have a Sparcstation 10 and had the same errors... what it didn't like was the termination on my SCSI CD-ROM. That would even kill the hard drive booting (same on my SGI Indy). Unfortunately, no combination of external terminators or in-line ones could solve the issue... had to use a completely different drive, which is dumb because the one I had been using was in an actual Sun external case (I think what ended up working was an AppleCD 300, the internal version, in a noname external enclosure). No wonder I hate SCSI. After vowing never to deal with that again I ended up spinning up a Linux VM to netboot via RARP and BOOTP, which is (relatively) easy for getting the installer going on anything not Solaris.