Avast is not working proberly

Soon I try to run a Scan, doesn’t matter which one, my Avast is crashing and I have to restart the Computer
I have Avast Premier and run Windows 7/Firefox
I removed the App and re installed it , but I still have the same problem.
Any Idea what I can do?
Regards
barbwarman

any other security programs installed?

follow instructions here https://forum.avast.com/index.php?topic=53253.0
attach Malwarebytes and Farbar Recovery Scan Tool logs … 3 logs total