Hi norman_8057,
Thank you for reaching out, and sorry about the trouble caused.
Please share more information on what you mean here by "documents disappear from computer screen after a few seconds." Are you referring that the PDF closes after few seconds of launch?
If yes, please try the troubleshooting steps suggested in the followin help document: https://adobe.ly/3WM1JM3.
Try reinstalling the Acrobat using the steps suggested below:
-Remove the application and run the cleaner tool (https://adobe.ly/3Jkry2G).
-Reboot the machine
-Install Adobe Acrobat from the following page: https://adobe.ly/42SPL6V;
Let us know how it goes.
Thanks,
Meenakshi