Generally, this is because your machine cannot reach the CD-ROM during the GUI phase of the installation. The file is found at:GLOBALROOTDEVICECDROM0I386NT5INF.CA_
You may still not be able to get to it and complete the installation since the CD-ROM driver or firmware is out of date. You will basically have two choices:
1) Go the hardware manufacturer and download the driver/firmware and apply it to the machine. You will want to hit F6 at the beginning of the test mode setup so that you can put the CD-ROM driver from the manufacturer in.
2) From a Windows 95 or Windows 98 machine, create a startup disk with CD-ROM drive support. You can then boot your machine to a DOS window, copy the I386 folder from the Windows 2000 CD-ROM to the hard disk, and finally run Winnt.exe from the copied folder to install Windows 2000.
This was first published in April 2001