I'm sorry to hear that you are having trouble with JuiceboxBuilder.
I hope my notes below help.

The first thing that I can think of which might be causing your problem is a background update to an anti-virus program.
If you have any anti-virus programs installed (e.g. Avast or AVG), then please try temporarily disabling them to see if this makes a difference. If any such program is interfering with JuiceboxBuilder's functionality, then disabling them (at least temporarily, for testing purposes) should help.
If you find that this resolves your problem, then please let me know what anti-virus software you are using and the version numbers of both the program itself and your current virus database and I will contact the company on your behalf and file a false positive report so that JuiceboxBuilder's reputation can hopefully be cleared in their next update.
(Please disable any security software at your own risk and be sure to disconnect from the internet first.)

If this suggestion is not applicable to you (if you do not use any third-party anti-virus software) or makes no difference, then I would recommend completely uninstalling and then reinstalling Adobe AIR.
As the problem happens to both JuiceboxBuilder-Lite and JuiceboxBuilder-Pro, it is unlikely that a similar problem has happened to both applications simultaneously.
It seems more likely that there is an underlying problem with Adobe AIR (the platform on which the JuiceboxBuilder runs) on your system.

There have been a few reports over the last couple of days regarding the latest version of AIR (v33.1.1.444) causing problems (the inability to install JuiceboxBuidler rather than the symptoms you report) so I would recommend using the previous stable version (v33.1.1.385) instead.
Unfortunately, Harman do not make older versions available for download on their website but v33.1.1.385 is still available here: https://www.filecroco.com/download-adobe-air/
I have confirmed that the file is genuine and clean. (I found the SHA256 hash for the file on an archived Harman web page and it matches that of the file from filecroco.)

If, for any reason, you cannot uninstall Adobe AIR (which might be the case if you have already attempted to update to v33.1.1.444), then please delete the following folder before installing v33.1.1.385.

• C:\Program Files (x86)\Common Files\Adobe AIR

I hope this helps.

Thank you for the update.
I'm sorry to hear that you are still having problems.

That's normal and expected. When using the new Harman AIR runtime, you'll see the Harman splash page when running any AIR application.

Something must have happened for this problem to have occurred and if you don't remember doing anything yourself, then perhaps some other background update has somehow caused the problem.
Perhaps you could use System Restore and restore your system to a point in time before the problem first happened.

Otherwise, knowing that you've already uninstalled and reinstalled Adobe AIR, I'd now recommend a full uninstall/reinstall of JuiceboxBuilder-Pro (and JuiceboxBuilder-Lite).
Check out the procedure listed as #11 in this forum post.
Be sure to manually delete the folders listed between uninstalling and reinstalling.
This is very important. If there is corrupt data in the ELS folder, then deleting it may help to resolve the problem.

When following the procedure for JuiceboxBuilder-Lite, just replace all instances of 'JuiceboxBuilder-Pro' in the instructions with 'JuiceboxBuilder-Lite'.