" Answer Drives mapped using the SUBST command are not visible to processes running as the local system account. This includes the Windows Installer engine. To enable non-administrators to replace drive letters and have the system utilize those same drive mappings is a breach of security. Drives mapped from the logged-on user's context are not visible to system processes in Windows 2003. This restriction does not exist in Windows 2000 or XP. If the drive to be used for the Notes installation can be substituted or mapped using a system process such as a machine logon script or an "AT" command, then the Windows Installer engine will recognize the drive letter and the Notes installation can complete successfully. ">