Hallo, we have discovered an issue in new WebShield implementation. This is probably reason of your problems. We are preparing fix for that.
Meanwhile you can try to switch to old WebShield implementation. To do that, please
Go to C:\programdata\avast software\avast directory
Find the WebShield.ini, file and add following lines:
[General]
UseStreamFilter=0
Now restart „avast! Antivirus“ service, or reboot.
Please let us to know if the problem is gone.