You need to ignore files of size less than 1,000 KB or 1 MB as these files are mostly virii & spam. See
WARNING: Viruses on network you should be aware of! (click on link) & get Norbie to solve your problem for you. For a direct link to Norbie see
NorbiesWorld (click on link) BUT, still see the other link as it has many suggestions & online virii scans, etc.