Hi, To anyone still having this problem
I have just received this reply from AVAST support
"We apologize for the inconvenience. In the latest version of Avast Internet Security, the scan engine has an ongoing issue. The concerned team is currently working on a solution for this issue and will release a fix soon. Hence you are facing this issue
However, your computer will be protected with Avast Firewall. We also suggest you to try repairing the Avast program and check the issue" .