Thus spake Thomas Wheeler <twheeler@asciences.com>:

after the download, when I either click on 'Open' to start the .exe, or if I simply download and doubleclick on the .exe, there's a blue install screen & a tiny popup that says 'Corrupt installation detected'. Should I simply back off to the previous version?

That won't help. The problem is that you are not running the installation executable with sufficient permissions, i.e. Administrator. As you should typically not log in as an Administrator-equivalent, I suggest you Shift+RightClick and use 'Run as...' to run the installer as an Administrator-equivalent user.

Thank you in advance for your help.

I'm happy to be giving instead of receiving, for once. :-)