Every once in awhile, when I hit enter, a page shows that is some advertisement, and the page has nothing to do with the topic or site I am at. I understand this has something to do with a particular virus, that it acts this way. My virus checker always comes up clean, so this is some residual action. I am using Avast, which has proven to be a good filter, but this one got in between when one antivirus system expired, and Avast was put in. Ideas on how to get this action stopped?