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.
thank fro your help.
I did as you wrote but I have the same issue. Have you another suggest?
Well, you can also try creating new catalog Or reinstall Lightroom software.
I did it but I have the same issue. I haven't any problem using v6.0 Why?
Thank in advance for your help