Recently switched virus scanners (again) and already thinking that I made a wrong choice doing it. Either way, you might want to clear this up with avast.
Program version: 2014.9.0.2018
Virus definitions version: 140626-1
Number of definitions: 2,311,163
If you could, when you create an answerhub post please let us know what order you installed the programs as well as what version of avast you are using. Have you attempted to add the Unreal Editor to your Avast’s exception list? Any other information you can provide to help us repro this would help us to find out what is going on. Thank you!