Instant messaging, the quicker-than-e-mail alternative for online communication, is moving rapidly from teenagers' bedrooms to mainstream America. And with it, IM is bringing a dark <A HREF="http://www.newsfactor.com/story.xhtml?story_id=43827">new legion of computer security problems</A> that could eventually be worse than the worms, viruses and other Internet maladies that already haunt email.