What Operating System are you using ? is it up to date ?
What avast! version are you using ?
Current version is 19.8.2393 (build 19.8.4793.541)
Has anything changed on your system recently ?
Do you have any other security based software installed ?
I'm not experiencing this on either of my systems.
Have you tried a system reboot, if that doesn't make any difference try an Avast Repair.