IT already told me that the servers were clean. The Advertising Department has reached out to the advertisers to see if they are running a pop-up.
Not much more I can do personally at this point. I haven't gotten the ad myself.
Next time someone gets the ad, see if you can right click and view source code. Pasting us the code will help figure out where the problem is originating from. The clues could also be embedded in the source code for the page you are leaving and the page you are navigating to.
I know this is a lot to ask of our users, but we are simply unable to duplicate the issue. I'm not saying that it doesn't exist...I'm saying we haven't seen it.