Electronics giant Sony has seen its share price fall after laptop batteries it supplied to computer maker Dell were deemed a fire risk.
No injuries are thought to have been caused
Dell is to recall 4.1 million of its notebook computer batteries because of the problem.
Sony said it did not know how much the problem would cost but that it had "taken steps to address the situation... to Dell's satisfaction".
The computer maker said it would continue using Sony as a supplier.
Most of the lithium-ion batteries are in computers sold in the US.
However, more than one million are thought to be elsewhere.
Dell says it knows of six instances since December when the batteries, made by Sony, overheated or caught fire.
The problem batteries were made by Sony Energy devices based in Fukushima, north of Tokyo, and were placed in laptops shipped between April 2004 and July 2006.
Batteries used in Sony's own laptops do not cause the same concerns because the problems only develop when used with specific types of computer, a Sony spokesman said.
In Wednesday trading, Sony shares fell as much as 2% at one point before recovering, closing 1.2% down on the day at 5,150 yen ($44; £23.45).
Morgan Stanley estimated that if Sony had to pay all the expenses of the recall, it could reach 50 billion yen.
The Consumer Products Safety Commission (CPSC), the US body responsible for consumer safety, says it is the biggest recall of electrical products in its history.
A CPSC spokesman said users of affected laptops should only run the machines on a power cord.
Alex Gurzen, the vice-president of Dell's product group, told the BBC the firm wanted to "put customer safety first despite this being a small handful of incidents".
Dell is offering affected customers free replacements and by late on Tuesday, had taken 77,000 orders for new batteries.
It also received more than 100,000 phone calls and had 23 million visits to its website, www.dellbatteryprogram.com, which tells people how to check whether their computers are affected.