Hello,
Sorry for delay in response.
We have found that on some systems the registry key mentioned above is stored within a GUID folder in HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\DynamicsNav71, instead of in the Dynamics71 folder itself. I believe if you add the reg key as described above then this should resolve the issue.
If issue is unresolved, please email support@equisys.com and we will investigate further for you. I will post an update here when we find resolution.
Kind regards,