JULIAN GREEN thought his PC was possessed. One evening in September 2001, his 7-year-old daughter dashed out of the family computer room in alarm and told him it had started showing her nasty pictures. He found that the computer's homepage had somehow been reset to a child-porn site. He quickly changed it back, but every couple of days it happened again. At the same time the errant machine started calling his internet service provider to access the site of its own accord.

In desperation, Green called in a computer consultant he found in the local yellow pages. The consultant was equally baffled by the problem and jokingly put it down to "demonic possession". Eventually, by reloading some software, Green managed to make the porn go away, but the computer was still prone to strange behaviour and unprompted dialling.

Then, just when Green thought the worst was over, things got considerably ...