Yes, this was a false positive, meaning we mistakenly flag a clean file as malicious. These things unfortunatelly happen 
Try manually updating Avast, then disabling and enabling all shields (right click tray icon -> Avast shields control). Let us know if it helped 
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I am still getting this false positive on the Outlook Inbox page on my computer (on two separate outlook accounts) but on my wife's computer there is no issue. Both computers were updated per instructions and are currently on database 160503-1 and program 11.2.2262. Have disabled then enabled shields. Disabling the web shield on my computer allows the page to work ok
I've raised a ticket but not heard back yet - I have posted to keep this alive in this thread and to see if others are still getting this "error"
I think the script causing the problem is more than likely on the advertising panel on the right of the Outlook home page screen. This is probably tuned to your click history / advertising preferences so I suspect that ensuring the warning is fixed might not be as easily reproducible as if it were part of the Inbox page proper.
Update: clearing Firefox cache does not help. On IE, the warning does not pop up but the page has frozen and the ads bar does not appear, so it's still beign blocked /Update
