A massive Internet outage that swept across Asia and slowed down service in the United States and northern Europe subsided Sunday, caused by a so-called “Slammer” message worm that could easily have been avoided, experts said. Reports of a near universal shutdown of the Internet in South Korea Saturday were accompanied by widespread problems in the United States that shut down some automatic bank teller machine networks, held up e-mail, cut voice-over-Internet service and disrupted many private businesses, including some newspapers. Hong Kong, South Korea, the northeastern United States and northern Europe appeared to be hit the hardest. Japan and Latin America were the least affected, according to Matrix NetSystems, an Austin, Texas, company that constantly monitors Internet traffic worldwide. Full Story