As Ray Mears will tell you, knowing how to start a fire without matches is one of the most important survival skills.

Now, thanks to Sony, businessmen who find themselves shipwrecked on uninhabited shores or lost in rainforests might still survive without such bush-craft knowledge.

If they are stranded with the right Dell, Toshiba, Sony, or Apple laptop, there is a good chance, if they wait long enough, it might just spontaneously burst into flames.

They will not need to rub two boy scouts together, or cunningly fashion flint in to the shape of a lighter, if they are lucky enough to have one of these hi-tech tinder boxes handy.

Dell customers were the first to notice that laptops fitted with Sony's new "zippo" range of batteries had this rather alarming "undocumented feature", resulting in Dell recalling 4.1m battery units in August.

Shortly afterwards, Apple owners started reporting an alarming warmness in their groins whenever they used their iBooks, resulting in a 1.9 million recall of more Sony battery packs from their customers.

Next, Toshiba said it would recall more than 800,000 batteries for its notebooks, Lenovo announced plans to replace 526 rechargeable lithium-ion batteries that include cells supplied by Sony, and, just for good measure, Dell said would recall a further 100,000 more batteries.

Not wanting to miss the opportunity to look like a major league computer supplier, Panasonic said it would recall batteries for 6,000 of its units too, while IBM jumped on the bandwagon and recalling many of its Think-Pad models.

Sony initially insisted that its own Vaio laptops were fine, but last week decided its own customers deserved a new battery too, agreeing to replace them.

Sony assures us that only on rare occasions will microscopic metal particles in the recalled battery cells come into contact with other parts of the battery cell, leading to a short circuit within the cell.

Under even rarer conditions, this short circuit may lead to cell overheating and potentially flames, the company has indicated. The potential for this to occur can be affected by variations in the system configurations found in different notebook computers.

Despite only 47 battery fires being reported to date, exploding battery paranoia is spreading like wildfire across the globe. One incident where a truck driver's Dell burst into flames, igniting ammunition boxes in his vehicle, inevitably made the headlines and fuelled further public anxiety.

Virgin Atlantic has insisted Dell owners remove their batteries before boarding their planes, along with

Quantus and Korean Air, who have also banned the use of Apple's "hindenbooks" on their planes too.

To date, some 7.1 million firebomb batteries are somewhere in the post to Sony, who will replace them free of charge at an estimated cost of $410 million.

Rather predictability, Sony's share price went down in flames last week too.

* Chris is managing director of internet consultancy WAA WebXpress. This and other unedited articles can be found at E-mail