There are now three versions o ID available for both Mac and PC through Creative Cloud, CS6 (version 8), CC (version 9) and CC 2014 (version 10).
To get the latest version, quit the CC Desktop Application, then restart it and let it update.
Which version do you use? There are 3 different versions available in the Cloud. When you pay for it, you should install the latest version.
It might be problematic, if you run an older system version, which would not support the latest CC version, in that case you can't install the newest version. But with your version isn't it the case.
Thanks both for the quick response,
I haven't got time right now but will carry out process as you describe - I think you've probably identified the issue. Which is great as it looks like I can resolve it - my fear was that Adobe introduced PC / Mac incompatibility nightmare! Glad it's not the case..