This issue with Outlook and Avast seems to be common. I am no different. I have Avast Premium and have Outlook 365 which I went round and round to resolve blaming my ISP and Microsoft. I just realized that when I disable Avast Premium, any Outlook (365 or 2010) works correctly. I have 64 bit, Windows 10, and both Outlook version. The repair or certificate does not fix the issue. Only if I disable Avast or also disabled Mail Shield.
Please help me resolve without disabling mail Shield or the Avast Premium. Im ready to use another AV software. Thanks