Hi Todd,
Thank you for your answer.
Few days ago I contacted the PokerStars support, but nothing they suggested helped.
I uninstalled the app with AppCleaner(FreeMacSoft), downloaded a fresh app from PokerStars.com.
To install it you have to open a .dmg file that opens a window on the desktop with 2 icons in it.
One is the app the other is an alias of the Application folder. To install it you drag the app in the Application folder.
In a normal situation you get a pop up window asking you for permission to install the app.
In my situation the app was copied in the Application folder without the pop up. Then when I tried to
open the app it would crash unexpectedly.
This morning I tried something, I restored the app from Time Machine and I chose a date that I knew the
app was working. While restoring I got a pop up asking for permission to install in my Application folder.
The app works just fine now. 😀
Have a great week-end!