When you “disable Avast”…you mean disable the shield in the icon tray ?

Also to disable plug-in without Outlook go to FILE {tab}, then Options, then Add-Ins…see pic attached.
You can disable add-in there…but think you already proved (where-ever you disabled before) that Avast 9 is the issue.

COMMENT: I cannot believe that if Outlook Email does not work that this is not the #1 complaint on the Forum. I am personally shocked how poor this Avast 9/2014 release is with all the bugs. I’ve not given up on Avast but I’m still on V8 for all my home PCs and biz PCs (paid for) I’m still V8. I see issues on Firewall, VPN, Java, etc. but I spend almost 80% of every day on email thru Outlook…my life line. I must have it working and also scanning for Virus, etc. To me this Outlook issue is #1 reason I will never switch until fixed or if it drags on make the switch to other A/V. I’ve been doing reading on recommendations and I hate AVG…once the king but they did the same thing awhile back on major upgrade but worse…bricked TONS of peoples PCs. I’m an Avast fan but this V9 should never have been released…I sure hope they fix things quickly so I don’t have to make the change.
http://www.pcmag.com/article2/0,2817,2388652,00.asp