Just received this error popup:
My Norton subscription is current, and shows as such in Norton Management. Norton shows as inactive on the machine, though (this seems to have happened recently, while I was away at work). When I check this device in my Norton Account, it shows an expired trial--but when I try to install the Norton Internet Security services from there, nothing happens.
I know the obvious solution is to just log in to my Norton Account on the machine and reactivate my subscription...but since Norton seems to have been down for a few days, and the event that precipitated my digging into this in the first place was my wife getting a BSOD, before I do this I want to check first and see if this is a legitimate Norton error, or a phishing attempt by some rootkit that's seized control of this machine, which is going to harvest my Norton Account login credentials and use them to disable security on every device my family owns! (Yep--for those here who remember me--still paranoid!) 
I've already run Malwarebytes Free, and it turned up nothing suspicious.