DVD and CDROM not Recognized

Dell Dimension 4600 running XP Home. When you boot up it doesn’t recognize the CDROM and the DVD Drives. The is an Yellow ! when I got to the hardware under system, and I have uninstalled and reinstalled several times with the same results below under properties.
A driver (service) for this device has been disabled.
When I reboot after uninstalling drives, it sees them and acts like it is adding them, but I then check system again and it has the Yellow ! again. Any Ideas would be appreciated.

Thx………..rfm