Unfortunately, previous versions are not available for download. (All download links always point to the latest version.)
However, I don't think reinstalling v1.5.0 would help.
As far as I am aware, there were no code changes between v1.5.0 and v1.5.1 which should have any bearing on the startup procedure.
Tried other adobe air applications, they work perfectly.
Have you tried JuiceboxBuilder-Lite yet? Does it crash on opening (like JuiceboxBuilder-Pro does) or does it run correctly (like the other AIR applications you have tried)?
As far as I can recall, no-one else has ever reported the problem that you are experiencing (with any version) so it seems to somehow be unique to your system.
I really don't know what is causing your problem and I've already suggested pretty much everything I can think of.
Maybe if we could find out how the JuiceboxBuilder-Pro.exe file ended up in your C:\Users\Liam\Documents\JuiceboxBuilder-Pro\ folder, we might have a clue as to the nature of your problem.
Out of interest, what are the current contents of your C:\Program Files (x86)\JuiceboxBuilder-Pro\ folder?
This folder should contain the following:
icons (folder)
META_INF (folder)
presets (folder)
template (folder)
jbBuilder-Pro.swf (file)
JuiceboxBuilder-Pro.exe (file)
mimetype (file)
Here are two more suggestions:
(1) Try running JuiceboxBuilder-Pro not from the desktop shortcut but, instead, by navigating to C:\Program Files (x86)\JuiceboxBuilder-Pro\ in Windows File Explorer and then right-clicking the JuiceboxBuilder-Pro.exe file and selecting 'Run as administrator'.
(2) As you are currently running Windows 10 version 1809 (build 17763.615), try upgrading to the current version (version 1903, build 18362.239). The kernelbase.dll file will be updated when you upgrade Windows 10 to version 1903 and this might help to resolve your problem.
Being that you are currently experiencing difficulties, I should perhaps point out that there are other methods of creating Juicebox galleries which do not require JuiceboxBuilder-Pro, many of which use plugins for other programs (such as Lightroom or Photoshop). If you use Lightroom or Photoshop, you might like to give them a try. Please see the Juicebox Plugins support page for details.
You can also create a gallery manually using the sample 'web' gallery (from the Juicebox-Pro download zip package) as a template. Instructions can be found here.
I'd certainly check the contents of the C:\Program Files (x86)\JuiceboxBuilder-Pro\ folder, run JuiceboxBuilder-Pro via the right-click 'Run as administrator' option and upgrade Windows 10 (to version 1903) as the next things to try.