I have not seen this before, and it's not a ProSeries message.

That's odd for sure - especially since an internet search turned up nothing like it. Was that the exact wording? Was it a Windows Operating 10 System like message, an old school DOS like message or something modern and web looking?

If I were you, I'd

• Double Check McAffee and any other Anti-Virus/Anti-Mallware/Firewall software you have. Usually they all have some sort of log that shows activity they've flagged, with details.  There should be a record of the message, somewhere. If you do find any detail, post a screenshot here
• Perform a full system scan with McAffee