Hi there. I just recently opened a Yahoo account for the purpose of live chat with someone who does not have Gmail or other chat programs. Today, I signed in to check any messages there, and then went on to browsing the web, without having signed out from the Yahoo account. And as I was so browsing, there opened a Yahoo chat window on my screen from some unknown person, of dubious nature, to boot. What happened? How can I prevent this from happening in the future? Was my computer or my Yahoo account violated? There is F-Secure running on my computer. Explanations and help are much appreciated.