After this update (5/26/17), Windows Defender took over my security. The UI of Avast could not be accessed (gave a message of "embarrassment" for not being able to open). Could not be repaired--a "compatibility" issue message popped up. My computer froze several times trying to shut down WD and re-establish Avast. I had to restart the system by turning it off at the "off" button and restarting (which it did not do twice). When up again I uninstalled my registered Avast Premium. Am asking the community if anyone else has had this problem, and if, re-installing Avast P. will shut down Windows Defender successfully without further issues, as it did when I installed it initially.
Solved. Re-installation will return security to Avast. And there were no other issues. Just wanted to know from the community what to avoid if tried.
