I am unsure as to why your users encounter this behavior. You could suggest they do the following:
- start the installer, and when they encounter the error, they should not close it. Leave the error on screen, go to Windows Task Manager and look for the setup process in the Processes tab. Sort the processes by "Image Name", and look in the sorted list. The process should have the name of their package file. There should only be one. Please send us a screenshot with the process list in Windows Task Manager.
- also, are they running the installer from a removable media? If so, what media?