I started getting this message from my antivirus yesterday. It tells me you likely have an infected ad on your site. It's still happening today.
From what I read on the Symantec web site this had to have been installed by some program that got downloaded and installed on your machine. An ad on a website should not be able to trigger this warning. Please remove it via symantec.
According to my IT department, this isn't on my machine. They believe it is an ad, but it seems to have stopped. I'll report back if it start up again. They are recommending an ad blocker, but don't want to do that.
Customer support service by UserEcho