I've been getting a load of them recently after an update (on this site and others). It prevents many pages even loading properly, which is an irritation.
After a little digging, I've discovered this is what's happening: http://myonlinesecurity.co.uk/flash-player-alerts-or-warnings-when-using-internet-explorer-11-on-windows-88-1-and-windows-10/
So you'll need to sit tight for now, until they fix the issue.
Matriarch