A DDOS (distributed denial-of-service) attack of unprecedented scale that targeted an international spam-fighting organization last week ended up causing problems for Internet users around the world, experts say. The DDoS attack started more than a week ago and targeted the Spamhaus Project, an organization based in Geneva, Switzerland, and London that maintains databases of IP (Internet Protocol) addresses, domain names, and other Internet resources involved in spam, malware, and other abusive online activities.