I am trying to figure out if I have an infection of sorts or not. Although I primarily use Firefox, I do use Internet Explorer regularly as well. Over the last month or two, when using Internet Explorer, I have had pages (seemingly from apps.facebook.com, although this could be coincidence as those are the pages I most often access in IE) appear to try to redirect to another website (I see a blank page with a strange web address) (after the current page has been loaded for a while, not while first trying to go to the page) and a standard gray dialogue box comes up with some sort of fake virus warning, asking me to click "OK" to download something or run a scan. The message varies - once it was purportedly from ESET and another time from AVG, neither of which I use or have installed. I have always gone into task manager and terminated Internet Explorer from there when that happened. Each time it has happened, I have scanned with Malwarebytes Antimalware, Microsoft Security Essentials, Spybot Search and Destroy, and Vipre Computer Rescue (each of which I make sure are up to date; each were run from an administrator account/elevated to administrator privileges except possibly MSE). Each time I have not found a thing. It has been my assumption that it is being caused by an ad that takes advantage of Internet Explorer in some way (it never happens when I am at the same pages in Firefox). The frequency of occurrences is approximately once a week, and the recurrence of the issue makes me wonder.