Error: A required CD/DVD device driver is missing - when you start Windows 7 or Windows Vista from the setup disk

If your installing Windows to an older PC, the CD/DVD drive may not be compatible with Windows 7 and Windows Vista, the CD/DVD drive may need to be replaced.

Remove the DVD media and check for scratches, cracks or smudges that may make the DVD difficult to read, if the media is scratched or cracked, you must get replacement media. If the DVD is dirty or smudged, clean the DVD with warm water and a soft cloth. Be sore the DVD is completely clean and dry before re-inserting into the CD/DVD drive. Next, restart the computer and press any key when you are prompted and start Setup.

If your CD/DVD drive is not compatible with the Microsoft AHCI driver (msahci.sys), your disk controller may be set to AHCI in the system BIOS. You may be able to resolve the issue by disabling AHCI mode for your disk controller in the BIOS. There are multiple BIOS manufacturers and BIOS versions, you should check your system documentation or visit your PC manufacturers website for instructions about how to change this setting. 

Note: The basic process for changing the disk controller setting is to restart your computer and enter the system BIOS. The most common method is to press F2 to enter Setup, (different PC's may use a different key). On the BIOS screen, browse to the setting that offers AHCI, ATA, or IDE and possibly RAID. If the setting is set to AHCI, change the setting to ATA. Restart the PC to the Windows Setup disk

Warning: Incorrect settings in the System BIOS can cause your PC's function incorrectly. If you are not familiar with configuring the system BIOS, you should contact the PC manufacturer for assistance.