Acrobat pro xi documents automatically close

Hey Sharon!

I hope you are doing well and sorry for the trouble you had with Acrobat Pro 11.

Acrobat Pro 11 is old and out of support product as the security updates, patches, features are no longer available. Detailed information is available here: https://helpx.adobe.com/acrobat/kb/end-of-support-acrobat-xi-reader-xi.html

Adobe's recommendation is to use the latest version of Acrobat to get the security patches/updates and the latest features. 

You may try repairing the installation files of Acrobat from the help menu>select repair installation. Reboot the machine after the repair. 

Also, try updating the Acrobat 11 to the latest available update 11.0.23 Planned update, November 14, 2017 from the help menu>select check for updates, reboot the machine and check.

However, the above suggestions may or may not work.

I hope this helps.

Thanks,

Anand Sri.