Dear All,
thank you very much for all your replies. I followed all your suggetions, but without success and so I opened a ticket with PMDG support and they are kindly assisting me... I will let you know.
In the mean time, other problems have come out and I think my system is completely messed up. I think my only solution will be a complete format of my PC, so I will bring it to the original virgin status. yesterday, after installing P3D v2.5 I opened it and there was a strange foggy effect (the back ground black colour of the screen looked like gray, like brightness was not properly set, but it was not a screen problem... It was the program), so I will format everything.
What a mess!!!
Alessandro Zambelan