File-sharing software that installs adware, Web sites that attempt to compromise a visitor’s computer, and free downloads that install a host of other unwanted software — the Web has become a confusing, and sometimes dangerous, place for the average home user. A group of graduates from the Massachusetts Institute of Technology (MIT) aim to change that by crawling the Web with hundreds, and soon thousands, of virtual computers that detect which Web sites attempt to download software to a visitor’s computer and whether giving out an e-mail address during registration can lead to an avalanche of spam. Full Story