i am working on live linux distro equipped with linux-2.6.26 kernel when i boot this cd from Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz from Internal SCSI DVD-RW [as boot drive set into bios] the system comes to basic shell level. But there is no device node in /dev for the SCSI DVD-RW which i need latter to mount it some where in /mnt and to copy needed packages to RAM. Surprisingly when i boot the same system Intel(R) Core(TM)2 Quad CPU using the same cd but from externel USB DVD-RW everthing goes fine and DVD-RW device node is created in /dev (i am using udev for nodes creation). The live distro CD also works fine on older machine i.e Intel(R) Pentium(R) 4 CPU 2.40 GHz the one i have tested for . Any body knows wats going wrong inside ? Are wat kernel option i need to enable to get a running system with internal SCSI DVD-RW ? i am stucked and need help from you guys

Thanx in Advance
UNIX (out of box)