After playing around a lil I think I've figured it out.. [for me at least..]
The program that you're pointing to isn't registered correctly.
In regedit: Navigate to Computer\HKEY_CLASSES_ROOT\Applicationsand find your .exe name.
Navigate under its name to shell>open>command. In the Default change its location to the actual location of the executable, hit
okay and then try and reassociate the file type as you normally would.
Let me know if that doesn't seem to work.
I have the same problem but when I look in the registry in the list of applications I don't see the one I need (Family Tree Maker 2014.1). I see the file type in that same list (.ftm) but not the name of the program. When I click on the .ftm file type
line, I see
(Default) REG_SZ ftm_auto_file
I've re-installed the program and that didn't correct it. I also set up another user account and it works correctly there but this is my administrator account where it' not working.
Melvaduke