In December I bought and installed McAfee on my laptop. Since then, I haven't used it at my school. Today when I turned on my laptop, then McAfee window popped up, with a warning that says "The detection signature file is more than 30 days old." I've clicked the Fix button, and nothing changes. So I really have two questions. What is a detection signature file, and how can I get it up to date?!? Thanks!