This also happened to me upon avast updating from v8 to v9. I am unable to access avast’s UI to configure it due to this.

The OS is Windows 7, 64-bit. This didn’t happen in v8. Windows 7’s Action Center detects that avast is fine and running. Also, avast’s DeepScreen feature has worked on a software I tried. I’ve rebooted the computer more than 5 times already, but the issue persists.