Adobe says:
"Resolve errors related to the AcroCEF/RdrCEF processes of Acrobat/Reader"
Then propose:
"Solution 2: Whitelist the AcroCEF/RdrCEF processes in your antivirus software
Antivirus software can interfere or block the AcroCEF/RdrCEF processes. The processes reside in AcroCEF folder. Add the folder to the exception list of your antivirus software.
Note:
The steps below explain how to add exceptions to Avast antivirus software. If you are using different antivirus software, follow the instructions on the respective website, and add the AcroCEF folder to the exception list accordingly."
How to do this for AVG?