probleme d'affichage avec Acrobat Pro XI

Hi @maria_enrica_1181 , 

Thanks for reaching out, and sorry for the troubled experience.
As you know, this product was declared End of Life a long time ago. If this issue turns out to be a product bug, it won't be fixed. 
Following are some suggestions:

•  Repair Acrobat, To repair > Acrobat > Help > Repair Installation (Win only)
•  Try opening a file that used to work previously
• Try opening the file in Google Chrome or Edge browser and check if that works fine. 
• Share the file with us and will take a look
• Try installing Reader, a freeware application: https://adobe.ly/3P43WPp

Let us know if this helps.