When clicking “Add/Remove Windows Components” in control panel, it shows error “setup was unable to load the master information file” and rejects further action.
This error occurs when master information file %windir%\inf\sysoc.inf is missing. This can happen when system is restored from an invalid backup or malicious software has deleted important system files.
You can restore the INF file from another Windows 2003 server with the same service pack.
Some components like IIS may still be missing from the check list after restoring the INF file. You can try to restore %windir%\inf\iis.inf from a reference server to add IIS.
Restore the INF files mentioned above to fix the issue.