Please turn off the Graphics Processor from Lightroom Preferences.
Go to Lightroom Preferences from the Edit menu
Click on Performance tab
Uncheck the Graphics Processor
Let us know if that helps.
Have you tried the above steps, please let us know the outcome.
Thanks you very much for you email. Today I turned of the graphics processor like you advised in your email. I worked for a while in Lightroom and unfortunately it freeze 2-3 times ( when I tried highlighting pictures to export them) so I click "esc" and it work again. It looks like that Lightroom need a lot of time to process in between action, if it make sense. A couple of years a go I bought LR 5 and I never had any problems.
I wonder if it is because Creative Clouds is working with Internet and of course a lot of people use this system or plan. I'm probably wrong but one think is sure Adobe need to resolve this problem if they don't want to loose the market.
I'll work a few more days and see what's happening and let you know if it is alright. I'll use the same reply.
Thanks again for your help, Dom
12 Balcha Street
Holland Park Brisbane
Mobile: +61 (0) 415 298 259