I have a Dell Dimension 2350 that came with a 48x CD-ROM drive and a 48x CD-RW/DVD Combo drive. A few months ago, I switched from Windows XP home to the Xandros Linux distribution. I was working on a project to copy pictures to the CD-RW when both drives disappeared, although they would open and close using the manual button. As I had experienced a few quirky hardware behaviors while using Xandros, I decided try to do a reinstall to get to a dual boot with XP and Linux. So, I ran fdisk and fdisk /mbr and the system boots fine and the drive light on the CD-RW/DVD drive flickers as normal, but not the CD-ROM drive.
When I try to boot from a Windows98 boot diskette with CD support, the startup attempts to load a driver (MSCD001), but the driver load aborts, with the message: "No drives found. Aborting installation."
Then I tried the debug option in the setup function and it, too was unable to find either drive.
The CD-RW/DVD drive will still open with the manual button. I checked all the connectors in both drives and on the motherboard and they all were firmly seated.