Off the top of my head I'd start with the physical properties.
For example, Make sure they are
jumpered correctly.
Doublecheck the cable connectors. Some are marked specificly for master/slave/mobo.
Reseat the ribbon cables on the cd/dvd's, and the motherboard, even if they look ok.
Reseat the power connectors.
Do this first, to eliminate a hardware problem. Then move on to
troubleshoot bios
settings/OS/drivers after that is eliminated.
Let us know how it goes.