I have exactly the same problem
I've changed cables, IDE chanels, master/slave options but nothing helps.
I think the problem is in the Motherborad or in the CD-ROM itself, because when it's not working the CD is not recognized by the BIOS properly.
BIOS shows "NEC CD-ROM DRIVE:IDE 2.0" and when it's working the BIOS shows "_NEC NR-7700A"
My MB is Gigabyte 7VA rev1.0.
Can someone suggest solution ?