The PM notification popup won’t turn off – I can’t delete the message triggering it – and the long post I just wrote explaining it all didn’t get posted.
I logged out and logged back in – popup still happening – let’s see if this post “takes.”
Is this still going on? Is anyone else having this problem?
I do note that it is Groundhog Day. 
(Seriously, no one should be having problems.)
Sorry, I forgot to come back to this thread – this was happening during the weirdness of 8-9 AM EST, referred to in my “PM notification pissing me off” OP that you (correctly) locked.
I will mention, however, that the PM written at 11:04 that I just read isn’t marked as read, and the notification counter in the upper RH corner still says 1, though I’ve read (and responded to) it.
At least I seem to have successfully turned off the popup, so I’m not going to let this get my panties in a twist.