Just did Dread Legion skirmish and right after I opened chest I've got a Security Alert window.
There were no browsers opened on my computer and there were no other programs that access internet, Neverwinter was the only program for that.
Also today, while invoking on toons I've had to reconnect couple times, so it could be related.
Notice that the icon for Energon was missing, so maybe the game tried to download it and somehow triggered security alert:
Comments
If you view the certificate, does it say the name of the server?
And, do you have on-demand patching enabled? (I don't).
It hasn't happened again to me though.
Game options: