When a user tries to mount a CD-ROM on a third-party CD drive, mount(1M) fails with the above error, followed by the sr0: SCSI transport failed message. The CD drive probably comes from a vendor unknown to the system.
Third-party CD drives generally have an 8192 block size, as opposed to the 512 block size on supported Sun drives. Check with the vendor to see if any special configuration is possible to allow the drive to operate on a Sun workstation.