Over the past few months, you may have received a bounced e-mail that says your e-mail to a certain person was rejected — and you didn’t send that e-mail in the first place? In that case, the spam didn’t come from your computer — but from another infected computer that had your e-mail address. Experts now predict that over one-third of all spam comes from hijacked, innocent computers — if you don’t maintain your technological lines of defense, you could find yourself as the next big spammer.