Not knowing what operating system or browser you're using it's hard to diagnose anything. I run Windows and for a virus stopper I use Ad Aware by Lavasoft, which I believe is a German company. I use the free version. It's rather unobtrusive and I'm not plagued by virus or strange happenings. I do have to manually check for updates from time to time. I choose not to have it run on a schedule but manually run it every couple of days.
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