Cannot run Setup for Windows 2000

This is a Compaq Presario 5050. Setup has failed every time when it is copying dmboot.sys. I have used different Windows 2000 CDs. I have changed hard drives, cd-rom drives, and IDE cables. This is the first time this has happened, and I have no idea what could be causing it. What is dmboot.sys, and how can I fix it? Pretend I don’t know anything about Windows 2000.