Win 2000 Pro and CD-ROM

A customer has just upgraded from 95 to 2000 and the CD-ROM stopped working. I replaced the old one with a new 52x Diamond Data and iinstalled a couple of programs from CD and all seemed fine. Next time the computer was turned on the CD-ROM won’t read data disks. Suggestions so far have been to turn DMA on/off and make it a master/slave. It is a single drive on secondary IDE channel. Any suggestions please?