When you try to install Windows XP by running Winnt32.exe, Setup prompts you to insert the Windows XP CD-ROM, even though it is already in the CD-ROM drive?
This problem is symptomatic of an incorrect SourcePath registry entry.
To resolve the problem:
1. Start / Run / Regedit / OK.
2. Navigate to HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Setup.
3. Double-click the SourcePath Value Name, a string (REG_SZ) data type, and change the data value to the drive letter of your CD-ROM drive. If your CD-ROM is drive D:, change the data value to D:\.
4. Exit the registry editor.
5. Press the Retry button.