A worldwide replacement program started the last days for all the laptop batteries that meet certain specifications, regardless of the manufacturer of the laptops. (To show the interest surrounding this matter, it's enough to say that Dell registered 200.000.000 visits on their dedicated website). The mass recall seems to have been started by an explosion of a ThinkPad machine made by Lenovo, explosion that occurred at Los Angeles International airport.

The problems extend further than initially thought and Sony refused to say how many laptop makers use the potentially faulted batteries, or how many devices have been sold. Sony also declared that its global replacement strategy is not obligatory, and it would depend on the outcome of consultations with individual computer makers. More than 7.000.000 batteries were recalled until now, but we may be witnessing more as the time passes.

And now to the point. While Sony agreed that battery failures reflect a manufacturing flaw in the battery cells it supplies, it also continued to say that the problem was at least partly caused by the laptops themselves. "The risk of fire can be affected by variations in the system configurations found in different notebooks".

To sustain that, Sony's own internal investigation revealed, after intensive testing, that the company engineers had not been able to reproduce any battery failures themselves, suggesting that the cause may lie partly in the systems designs.

You can see more details here.