If your computer has two CD-ROM drives, and you perform a clean install using an Upgrade CD-ROM, you are prompted to replace the Upgrade CD-ROM, in the first CD-ROM drive, with the qualifying media CD-ROM. When you do so, you receive:
Qualifying operating system was not found.
This problem occurs because Windows 2000 setup searches the second CD-ROM drive for qualifying media.
Place the qualifying media in the second CD-ROM drive and tell Setup to search again.