Could you please open Activity Monitor and check if there is any process running for Lightroom ?
If yes, select the process and End it.
Also please make sure Lightroom is updated to the latest version : Keeping Lightroom Up-to-Date
No activity of Lightroom in Activity Monitor. No signs of activity after trying to open in CC. Latest update. Sorry.
Installed El Capitan. Problem solved. But funny that it worked om OS10.8.5 until Friday. Thanks for your advice, HarryC