I previously checked the post you attached before I wrote my own post.
I have no other installation beside NAV R2 CC and RTC.
I deinstalled and reinstalled my environment without success.
But I recognised that my NAV installation does not provide a registry key at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
There is no microsoft, dynamics or any other related key available under "uninstall".
The second registry key is available.
I tried to add the key manually, but as I don't know on which content (strings) the installation looks it did not work.
Actually I am stuck. :(