I blame temperance. Or work. Or my mother. Possibly all three together. Anyone, anything in fact, except for the real culprit: me.

If it hadn’t been for temperance I would never have been online at 10.30pm on a Saturday in the first place. Rather, I would have been downstairs, having a beer and watching West Ham United on Match of the Day, indulging in their usual bit of escapology down at the foot of the Premier League.

The thing is, though, that my doctor doesn’t seem to view the logic of alcohol consumption in the same way that I do. If the average adult consumes, say, 30 units per week then some will necessarily drink more and some less. That’s how averages work. So as my doctor is a Muslim and drinks nothing, then someone else, let’s say me, will have to drink more to keep up the average. But no. Irrespective of what it will do to the numbers, it seems that I have still got to cut down.

Then there was the work angle. (Isn’t there always?) With a crystal-clear, alcohol-free brain, why not have a look at one or two of those study skills websites I have been meaning to check out for months? “You’re doing what?” says Mrs Jones. “It’s Saturday night!” Her voice reverts to sotto voce, but I can still make out the word “saddo” from the muttered stream.

So there I am, sufficiently engrossed in the world of Intute and Chalkface that I don’t see it coming. Flicking between sites it’s suddenly there on the screen: “Security alert - your computer has been infected by a virus.”

In my defence I should point out that it came dressed in the clothes of my computer’s own security system. It looked so convincing. But then I suppose to an innocent child the big bad wolf might have looked convincing in the bonnet and cloak of Red Riding Hood’s grandmother.

Whatever, there was no escaping its lurid flashing and beeping. Virus attack! Virus attack! It was like that moment in the old U-boat films when the klaxon goes off, the light fades to red and the depth charges start exploding all around. So is it any wonder that I succumbed and clicked on the “fix this problem” box it was offering me?

Yes, I know. Now I know. That was about as wise as saying to a foot-in- the-door salesman: “Come on in.” Now the virus had taken hold and everything else on the machine was frozen.

Ultimately, all I could do, all it would let me do, was to tamely follow its directions. This took me through to an authentic-looking site apparently run by a company called Anti-Virus. If I bought its software - a snip at only $60 - the problem would be fixed and my computer would work again.

Obligingly at the bottom of the page was a section - also looking plausible - where I could type in my credit card details.

For one stupid moment I even considered doing this. “Yes, it will cost you pound;40 or so,” the little voice whispered in my ear, “but then you will be rid of it for ever.” Luckily for me there was an alternative little voice. This said that at best I would be spending a relatively small sum of money on worthless software. More likely I would be handing some malign little man in Lagos or Luton the freedom to use my credit card details.

Next day, I called in my computer-savvy son. “You did what?” was his response when I told him, under questioning, how it got on to the machine in the first place. After half an hour of enthusiastic clicking of the mouse, he managed to temporarily turn it off. Then he went online and found a hunter-killer programme to nail it properly.

As for the morals to be learnt from this sad tale: don’t work on a Saturday night. The other moral concerns alcohol and health. If your doctor advises you to cut down, think hard about the repercussions. The minute I did so I picked up an infection.