In the past, it was customary to install all software products in your C:\Program Files folder. That was common for Microsoft Access add-ins through Access 2003.
With Windows XP, and especially Vista and later versions, the default permissions for this folder was READONLY. This was implemented to prevent malicious viruses that changed the user's installed programs.
READONLY works for traditional executable (*.EXE) programs that are never supposed to change.
This doesn't work for Microsoft Access add-ins. These are MS Access databases and must have WRITE rights. For instance, it may contain tables that are bound to forms that are edited, or tables need to be relinked to another database. None of those features work if the database is in a READONLY folder.
The solution is easy: Simply install the program in a folder where the user has full permission to read and write.
For our products released in the last few years, when you install it for your individual use (does not apply when you install it for the entire machine), the setup program automatically selects a folder in your Users folder. This ensures you have the rights necessary to run the program. If you install it for the machine, it defaults to a folder name in the C:\ root folder.
You can overwrite this folder and install it anywhere. Some people with Administrator rights have chosen to install it in their C:\Program Files folder. You may think you have WRITE rights because you can successfully install the program in that folder. However, even with Administrator rights, this won't work unless you explicitly go into Windows and modify the User Access Control rights on that folder after installation. We don't recommend you do that just to run Microsoft Access add-ins and databases.