Yes, every Ledger device is given a secret key during manufacturing process. The key proves device's authenticity when connecting to Ledger's servers. If a device is not genuine then a warning is displayed. The same applies if the software was modified.
At least there would be verification for the authenticity which is good for us, the users.
This is first time I see such problem with Ledger Live, and by what you write it seems that something is preventing new version of Ledger Live to run on your OS. I guess you have this problem on W10, and not on W7?
I haven't tried it on W7 because I don't have that anymore. Anyways, I did remember that ever since that update, the previous version of Ledger Live is gone, even in the program files, there's no executable. I would also check some of the possible software that could interfere with the process.
Well, you don't need to check every single letter. Checking the first 4-5 and the last 4-5 is enough.
I think it's just the paranoid self in me that wants to see it, but I think doing the 4-5 letters is enough as well.
Possibly a "stuck" aka ghost process?
If you haven't already trying checking Windows Task Manager to see if there is a Ledger process still running in the background and/or try rebooting. Then try re-installing Ledger Live using the installer from:
https://shop.ledger.com/pages/ledger-liveWell, that's the thing, after installing the program, there is nothing left with the program files. But I haven't restarted my PC just to re-install it, I just used the Ledger Live on my laptop. I haven't had the chance to try it on my desktop.
I've read all the suggestions that you have. When there are updates, I never such problems like yours.
Anyway crwth, have you tried posting this on their reddit?
https://www.reddit.com/r/ledgerwallet/Luckily, you didn't experience it. I don't know what is happening but I haven't focused on it yet but maybe let's see later. I will try to post it on Reddit once I have screenshots of the problem.