I have a computer that did the same thing, I tried everything, except what actually worked. In the boot options, I had the choice or CD-Rom, SCSI, Floppy, IDE1, IDE2, IDE3, and IDE4. Anyhow, if I set it to CD-Rom, it would never boot fro mthe CD, but once I set it to the appropriate IDE channel (IDE3 in this case) it boot off the CD-Rom no problem. See if you have this option. Also try Atapi or what ever the name is for it (to tired to rememeber). If all else fells, it sounds goofy but if you only have one hard drive and the CD-RW is your second drive, set it as HDD1 and see if it works. I doubt it, but you never know.
It could also be a defective CD. I've had that happen in the past as well.
Daniel