Out of the blue, I found the attached message box posted on my desktop. I says that I may be a victim of software counterfeiting and to go online to resolve the issue.
Is this a legit message from Microsoft or do I have a trojan/virus/rootkit trying to gain control (of course I didn't select to go online to resolve the issue)?
That would be a generic message that you get when your Windows is no longer activated. See if you are able to activate online as usual. If not, then you could see if you may be able to activate by phone.