An odd one, that. Does the drive work OK? What is your IDE Device setup? Presumably the DVD Drive is a slave to your hard disk's master. Are the jumpers set correctly? Is the IDE cable pushed home firmly?
And what, really, do you need a CD-ROM drive for when the other two optical drives will perform the same function?
I'd seriously consider ditching the CD-ROM drive and just using the DVD-ROM drive and CDRW on the same IDE port (IDE 2, preferably) as master and slave.
If you need further explanations, ask away.