First, I'm sorry you are having trouble! I hope we can figure out what is happening.
Are all your users with these problems on Windows?
What happens when Spine cannot be opened? Is there anything in the spine.log?
If you are getting hard native crashes in your spine.log (as opposed to nice Java stacktraces), it's likely anti-virus or anti-malware interfering with Spine. Disable anti-virus for testing if possible. However, sometimes on Windows the name of the DLL that crashed is shown. If that DLL is a graphics driver (eg it has nv or amd or igd in the name) it can indicate a problem with the driver.
Spine uses OpenGL and relies on hardware drivers, so updating graphics drivers is the first thing to check after anti-virus. You can test that OpenGL is working with apps like GPU Caps Viewer, OpenGL Extensions Viewer, or benchmarks like FurMark or Unigine Heaven. Spine's OpenGL needs are meager and should be easily satisfied by any graphics card made in the past 10 years (OpenGL 2.0+ with the FBO extension).
If Spine was working for quite some time and only recently it started failing to run, what changed? Hardware, graphics drivers, Spine versions?
