866-616-4436

Yes I had a pop up on my computer that wouldn't let me exit and said the number for me to call to fix the problem was 1-866-616-4436 it said it was from Microsoft but when I checked with Microsoft they said that that was not one of their numbers. I think it was somebody who hacked my computer and possible got banking info. I don't think it was really Microsoft I called.

If you allowed them access then they got your information.  What happened was that you are using a unsecure browser, probably IE or the new Windows 10 one that are set to accept everything and anything that comes down the pike.  You went to a web site and what happened was that there was an ad there that put that message on your computer.  You need to start using a browser with an add on advertisement blocker and to also shut down Java.  I use Firefox with adblockplus and have never had a problem.

I had the same problem, talked to them and discovered they were cons, shut them down. tried to unhack my computer needed to go to a computer shop to get it cleaned out.