Call windows support Number 844-490-6711

I am running windows 7 on an Acer Desktop that is roughly 3 years old. When I try to click on anything, say an image, a pop up appears instructing me to call 844-490-6711, that claims to be windows support since I have a virus. I have an active antivirus and it shows no virus yet the message appears often. What is it and how can I solve it?
