I just installed ver. 10 of Avast (free). The programmers appear to have continued their march toward making it nearly impossible to figure out what the scans actually do. For example, now we have "Smart Scan". What's the difference between that and "Quick Scan"? What do each of these scans do differently from the other: Rootkit (very quick scan), Rootkit (quick scan), Rootkit (full scan)?? Am I endangering my computer by using "only" a very quick rootkit scan and not a full scan? Should I run Smart Scan once a week, a Quick Scan once a month and a Full Scan every 6 months? Etc., etc.