Thanks for your continued support.
Now I am even more confused as the symptom is identical in safe mode....
This means the problem is within juicebox itself.
As my last working version was 1.5.0 is there any way to get a hold of it?

Tried lite version - same problem.
Current content of the x86 folder is identical to the one you listed
Ran as administrator - same problem
Updated windows - same problem
Tried compatibility tests - same issue.

Frustrating as I have been using juicebox happily for years...

Tried all of the above...  None helps.

Tried other adobe air applications, they work perfectly.

How can I get the 1.5.0 version to try if 1.5.1. has an issue?

Reinstalled. Now at C:\Program Files (x86)\JuiceboxBuilder-Pro\JuiceboxBuilder-Pro.exe did not solve the problem.
Created a new admin account, clean. Same problem.

This is what I see in the event viewer

Faulting application name: JuiceboxBuilder-Pro.exe, version: 0.0.0.0, time stamp: 0x5cb7acf2
Faulting module name: KERNELBASE.dll, version: 10.0.17763.615, time stamp: 0x832170f2
Exception code: 0x40010006
Fault offset: 0x0011fd62
Faulting process id: 0x4b80
Faulting application start time: 0x01d53a5c617a2a8c
Faulting application path: C:\Users\Liam\Documents\JuiceboxBuilder-Pro\JuiceboxBuilder-Pro.exe
Faulting module path: C:\WINDOWS\System32\KERNELBASE.dll
Report Id: 246d0fe1-0c9a-4ab6-8dd1-4ac8ed4cb6b7
Faulting package full name:
Faulting package-relative application ID:

I just installed v.1.5.1 on a new Win10 computer (v1.5.0 worked on my previous laptop).
clicking to start I see the splash screen and then it quits.

Any ideas?