SAN JOSE – Susan Love's problems began with a smile. The New York City fund-raiser clicked on a happy-face attachment in a friend's e-mail last year. The virus crashed her computer within an hour. Love, 57, salvaged her data. But within a few months her computer's performance slowed to a crawl. In December 2003, she upgraded to a Sony Vaio with an extra-large monitor and Microsoft Windows XP operating system. Within a few days, "spyware" – programs that sneak onto computers uninvited – began sponging up valuable memory. Then her e-mail stopped arriving. Instead of crafting holiday e-mails, she spent...