hi, i just created a new computer and when i installed my dvd-rom drive and than my cd-rw drive neither of the drives are recognized. When i just install the dvd-rom and not the cd-rw it recognizes the dvd-rom and it works.
Sounds to me like a problem with jumper settings. Make sure that the drives are correctly jumpered and that they are in the right place. Try to put them in the same array as they were in originally.
Install them on different IDE cables. For example, install the DVD on the IDE-0 as a slave and the CD-RW on the IDE-1 as a slave and see what happens. Some MOBOs don't like installing similar devices (Optical or HDDs) on the same IDE.