Hi,
Thanks for your answer.
As for the Mac installation I suspected it was so, so now it's been confirmed.
Eventually I manged to get Audition CS6 to work on my Windows 10 platform, this time taking a different installation approach.
After removal of all traces from previous Audition installs I proceeded as follows:
1) created a new folder for the installation on the C: drive (C:\Audition) and gave myself all security privileges for that folder and whatever would be created below that folder.
2) instead of using the downloaded file (Audition_5_LS7.exe) for the complete installation I used the Set-up.exe from the extracted installation set (running Audition_5_LS7.exe creates a folder Adobe CS6 - default on your desktop - containing all installation related files).
3) running the Set-up.exe as administrator I selected the C:\Audition folder to be the installation folder instead of the default C:\Program Files (x86) and installed Audition as a Trial version first.
The trial version (run as administrator) just worked perfectly, so I activated it (licensed it) using my serial number.
And now all is back to normal 
rgds
Søren