The virus is most probably on your moodle server, not your machine. I suspect you will start seeing this happen on different browsers. I had this happen on my server too. You need to search your courses and front page for the link that you are being directed to. I found that some teacher had inadventently put some something in a course description (or been hacked and someone else had) and the ads popped up everywhere.
As for single view, can you tell us the exact process you are using. It works just fine for me - I am on 3.0 though so possibly an early bug. What happens when you put the zeros in? Are you checking the override box first?