You'll need to pop them into another CD-ROM drive to find out for sure, but it's possible that the problem is in the CD-ROM disc. Your relatively ancient drive may have a hard time reading higher-density (74-minute) CD-ROMs or discs that mix audio and data tracks or contain a zero track. I've also read reports of people having difficulty reading CD-ROMs formatted using Microsoft's Joliet CD-ROM file system. Joliet extends the standard ISO 9660 CD-ROM file system to support Windows 95-style long filenames. If the CD-ROM drive's contents include filenames longer than 8 plus 3 characters, this could be your problem. On a related note, it's also very likely your drive will have trouble reading CD-Recordable discs (identifiable by their gold colour).
Having said all that, it's much more likely that your drive is simply dirty, or tired. The laser it uses to read data from the CD-ROM has a lens that may have accumulated dust and other crud in its many years of use. Before you explore more expensive solutions, consider buying a CD lens cleaner at your local computer store. They only cost a few dollars, and consist of a disc fitted with gentle brushes that you pop into the drive for a minute or so. A co-worker might even have one you can borrow.
If cleaning does no good, and the CD-ROM itself doesn't appear to be the problem, the prognosis goes from bad to worse. The drive's laser or motor is probably on its last legs, in which case your best move is to replace it. But this news isn't so bad -- newer, speedier, and more capable drives are inexpensive.
- Scott Spanbauer