By Joseph Menn SAN FRANCISCO (Reuters) – Microsoft Corp said on Thursday it had disrupted the largest network of compromised personal computers, involving some 2 million machines around the world, since it stepped up its battle against organized online criminals three years ago. The Redmond, Wash.-based software giant filed a lawsuit in Texas and won a judges order directing Internet service providers to block all traffic to 18 Internet addresses that were used to direct fraudulent activity to the infected machines. Law enforcement in many European countries served warrants at the same time, seizing servers expected to contain more evidence about the leaders of the ZeroAccess crime ring, which was devoted to click fraud. Such rings use networks of captive machines, known as botnets, in complicated schemes that force them to click on ads without the computer owners knowledge. The schemes cheat advertisers on search engines including Microsofts Bing by making them pay for interactions that have no chance of leading to a sale.