The Zeus botnet was switched off, but as its hacker operators pulled the plug they also self destructed more than 100,000 infected computers in the network.

According to the Washington PostZeus/Zbot was a software kit that sprung up in March that harvests financial and personal data from PCs through the use of a Trojan. It did jolly well because it managed to make each installation appear different to virus trackers so that it would be more difficult to remove.

However Zeus also had a "kill operating system" and when the operators decided to shut the botnet down it was actually executed some time last month. Activating the Kill switch resulted in a bluescreen and subsequent difficulty booting the OS. However it did not do much else. 

It is not as if the hackers were trying to cover their tracks because  the Trojan binaries and the startup registries were still there. In fact the infected computers will still run the trojan and will start re-establishing the botnet.

Quite why the hackers wanted the botnet switched off for a couple of days is anyone's guess.