Mysterious unidentified error message I keep getting this error on my Mac (see attached screenshot).  

It happened yesterday and now today again.

The dialog is not associated with any application (at least, when I select it, it does not change the menu bar). In exposé the app title that it is given when mouse over is "UserNotificationCenter".

I can't find any info about this error on-line and I wondered if anyone had any ideas or any way to investigate it further.

Running 10.11.3.
I'm not sure, but it looks suspicious. Poorly written, use of exclamation mark, reference to "PC" - it all looks weird. It's pretty useless too - you get an "OK" button and nothing else? What sort of dialog is that?!

Maybe check your date/time settings, but if there's no problem, I'd be a bit concerned about malware. Did you install any software recently?