Wrench:
The desktop and one laptop are both Windows Ultimate, and the other laptop is Windows Home Premium. Meant to include that in first post.
So should I look at the program file for the loaded-but-not-operating program the same way, i.e., set its permissions for all users to full control? I see that Authenticated Users and Users (computer name\Users) each do NOT have Full control, but SYSTEM and Administrators (computer name\Administrators) do show Full control as well as read, write, modify. But this configuration is also the same on the 2 laptops. Hmmmm.