It sounds like an underlying problem with Adobe AIR.
I'd try uninstalling and then reinstalling Adobe AIR to see if this helps.
You can download the latest version of Adobe AIR (v33.1.1.385) from Harman's website here: https://airsdk.harman.com/runtime
If this does not help, then try uninstalling and then reinstalling JuiceboxBuilder-Pro, too.
Between uninstalling and reinstalling, make sure that there are no files left behind from previous installations by manually deleting the following folders (if they exist on your system).
/Applications/JuiceboxBuilder-Pro.app/
/Users/Username/Library/Application Support/Adobe/AIR/ELS/JuiceboxBuilder-Pro
/Users/Username/Library/Preferences/JuiceboxBuilder-Pro
I hope this helps.