This can occur on install if a different SKU of Delphi of the same version of Delphi was not completely uninstalled. The MSI still thinks that Delphi is installed. To resolve this, run regedit and navigate to HKEY_CURRENT_USER\Software\Microsoft\Installer\Products and do a search for Borland. One of the subfolders will contain a reference to the version of Delphi that you are trying to install. Export this subfolder as a safety measure and then delete it from the registry. Then, try to install Delphi and you should no longer get this error message.
Last Modified: 28-MAR-03