The much-maligned remake of The Omen has set me thinking about how much control I exert over my computer. Increasingly, my PC acts like it's in thrall to a wicked influence. For example, last night, an XP flag popped up onto the screen telling me to download an 'update'. Given the choice between 'standard' and 'custom', being a pedant, I went for the custom installation - and was glad I did. It turned out to be a patch that would detect whether my version of Windows was legal. I assumed it was legitimate but, since I had bought it from the little PC shop round the corner, felt unsure. So I cancelled the update then went to bed, only to be woken at 2am by the tinkling boom of a restart. Oh no. Windows XP had decided to overrule my decision and install the update anyway. All's well, except I do wonder how much power I have over my computer. It seems light years away from my original model - an Amstrad word processor reliant on keyed commands and little more autonomous than an eraser. The darn thing hisses at me intermittently. Windows are forever popping up demanding my attention; now and then a flag carrying an alert appears in the bottom right-hand corner. Downloaded files suddenly unravel. Spasmodically, the screen flicks into screensaver mode: an onrush of stars. Sure, deep down my PC is a cabbage - possessed with minimal if any artificial intelligence and devoid of consciousness: the fuzzy sense of identity and will that just about serves to distinguish us from machines. But control of the thing appears to be insidiously slipping from my grasp. In the worst-case scenario, a hacker uses a virus to gain remote access to a computer and drops a slice of malicious code known as a bot. The bot tells the computer to secretly log into an online chat room frequented by other zombies and obey instructions issued by the chat room's controller: usually the person who wrote the bot virus. The computer is then what you call a 'zombie'. In pulp fiction, heroes dispatch zombies via dismemberment or destruction of the brain and/or upper spinal column. Sometimes, the entire body of the monster must be destroyed, usually by burning. Shotguns are the zombie-killing weapons of choice. But explosive weapons such as grenade launchers get a look-in too. The best way for you to prevent bot infection is to keep Windows and your antivirus protection up to date and leave the rest to the authorities. In May, South Korean officials arrested a man suspected of running a 16,000-strong network of zombie computers. According to the state-backed Korea Information Security Agency, the suspect is believed to have sent 18 million spam e-mails to 133 countries every day from his network (or botnet) of compromised computers. One down, how many to go? Probably quite a few because you need disturbingly little technical knowledge to launch attacks. You simply nose around a little to find the places where you can download the tools, then basically point and shoot. An unprotected PC is then effectively possessed, obliging an exorcism.