For the last few days I’ve been trying to upgrade my Adobe Lightroom install to 1.4.1, but was met with a dialog box proclaiming that Adobe_Lightroom.msi could not be found, and prompting for a new file path. The default path in the picker was a path into Documents and Settings\{username}\Application Data that didn’t exist.
Tonight I found this thread on the Adobe support forums that pointed me at a Microsoft Support Article that provided a download of the Windows Installer CleanUp Utility. I ran that, cleaned up the original Lightroom install, and was able to upgrade to 1.4.1. Problem solved.
This stuff is getting way too complex.