The Sasser worm began to spread on Saturday, and unlike a virus does not travel through emails or attachments. <A HREF="http://news.yahoo.com/news?tmpl=story&u=/afp/20040502/tc_afp/internet_virus_040502191735">Spreading by itself</A> to any unprotected computer linked to the Internet, it attacks through a flaw in recent versions of Microsoft's Windows and causes the computer to shut down, then rebooting it, repeating the process several times, but appearing to do no lasting damage.