IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:
256986 Description of the Microsoft Windows Registry
When you try to install Windows XP, you may be prompted to insert the Windows XP Professional CD-ROM, although the CD-ROM is already in the drive.
This issue may occur if the registry entry that specifies the path to the location of the Windows XP installation files is incorrect.
WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk. To resolve this issue, change the registry entry that specifies the path to the location of the installation CD-ROM: