I have some additional information. FYI, I am no longer running SU as administrator.
I have found the behavior that seems to trigger the Windows Installer problem. If I open SU and select a file to open, everything opens and starts fine, no problem and as expected.
However, if I go to directly to a file first and double-click it to open and start SU, the Installer is triggered. Obviously, I have SU identified as the app associated with SKP extensions. This Installer misbehavior does not occur with any other programs except SU and LO. In other words, if I click on a Word file or Excel file or PDF file, the appropriate app opens and starts without problems.
Does this happen to anyone else on Windows machines?