A mi eso me pasó también hace tiempo, justo cuando instalé en mi windows XP una versión no original del Nero. Para solucionarlo tienes que seguir estas instrucciones que te pongo aquí, cambiando algunas cosas en el registro. ES fácil y se soluciona rápidamente.
Tips and Fixes

 

Uncover Windows XP Product Key - If you have more than one system running XP you have obviously purchased more than one copy of the Operating System. However you may have forgotten which Product Key you used for which system. It happens. I have 5 systems and have had all three running XP at times. As you know XP does not store the Product Key in a recognizable format in the registry as Windows 9x/Me does. The app ViewKeyXP is your salvation.

System Cannot Access CD-Rom, CD-Recorder or DVD Devices
If you uninstalled and reinstalled Nero in XP, or did an upgrade from a previous OS to XP without uninstalling Nero first, this is a known error (for both Adaptec and Nero). There is a  problem caused by an association created in the system registry between some Adaptec driver files and the CD file system drivers for Windows 2000/XP. If the Adaptec driver files are renamed or removed, then the system will loose access to any CD drive (CD ROM, CD recorder, or DVD)
Check here before trying the fix below

IMPORTANT: The following contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. If Windows XP won't start  you can restore the registry by rebooting while pressing the F8 Key. Select "Last Known Good Configuration". Or you can use "System Restore" from Start->Programs->Accessories->System Tools.

1. Uninstall all CD Burning software from the system.
2. Go to the RUN line and type in Regedt32 and press Enter.
3. Go to the following registry locations and delete the key values for UPPERFILTERS and LOWERFILTERS (Do NOT delete the entire 4D36E965-E325-11CE-BBFC1-08002BE10318 key just right click the individual keys and select Delete)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\{4D36E965-E325-11CE-BBFC1-08002BE10318}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002\Control\Class\{4D36E965-E325-11CE-BBFC1-08002BE10318}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318}

4. Close out of Regedt32.exe and reboot the computer.
5. You should have access to your CDROM drives after reboot.

Make sure you create a System Restore Point before you make changes to the registry.
 
Suerte.