I know this is an older thread but I just thought I would add something. The virus warning that you saw on their screen could very easily have just been a pop up add. I have seen many pop up adds that look very professional and official, and are designed to make people think they are getting a message from their own system.

Many of them look as though they are performing a scan of your system. If the person is fooled and then clicks into the add, they can be redirected to all kinds of things from an add or trial for antivirus software, to downloading a virus onto their system.

If you get a virus warning that you don’t recognize, just get off the internet and then scan your system with your own antivirus software.

Having said that, there are many threats that common antivirus software will not detect. So it is also possible that you can be infected, and then your own antivirus scan comes up clean. In a situation like that, where you think something may have happened but you can’t detect it, using a more robust online one-time scan from a reputable company is a good idea (As Jo*mar already said and also already provided links to a few).

I hope this helped a little, although I see Jo*mar is already the resident tech here. God Bless You.

Bernclay-