When it comes to area businesses affected by the recall of batteries for Dell's laptop computers, a non-business is near the top of the list: Roanoke County Public Schools.

The county had purchased nearly 1,600 Dell laptops for use by high school students and teachers, as well as for staff and computer labs in the elementary and middle schools.

Each one has to be checked for a potentially bad battery. Any found will be shipped back to Dell, and users will be stuck with using a power cord until replacements arrive. That could take up to 20 days, according to Dr. Jane James, director of technology for Roanoke County schools.

James sent out a release to affected students, explaining how to check their batteries and, if their laptop has a defective one, to remove the power packs and turn them in on the first day of class.

Meanwhile, James' office is checking the staff's computers one at a time, although she's not worried. "No one's even been shocked," she said.

"My stand is, although I think the risk is almost nonexistent, we're going to check all the batteries. If they're on the replacement list we're not going to let the children use them."

James said her staff will also check the students' computers when classes begin, even if students say their computers are safe.

"They may not tell us the truth because they may want to keep their batteries," she said.

Despite what James described as "a little bump," she said she thinks it will cause no disruptions. And the school system has no plans to switch from Dell computers.

"Dell is absolutely not the only vendor affected by this," James said. "They're the only one that's stepped forward."

Overheating of lithium-ion batteries is typically caused when circuitry designed to control the output of the individual cells in the battery is faulty.

The result is known as "thermal runaway."

While Dell's current recall has attracted attention because of its size -- 4.1 million units -- the problem is by no means limited to this incident or to Dell.

Dell had already recalled a total of about 333,000 laptop batteries in December, May 2001 and October 2000 for the same reason as Monday's recall.

Hewlett-Packard had to replace 150,700 batteries in recalls in April and October, and Apple computer recalled 156,000 of its iBook and PowerBook laptops in May 2005 and August 2004 -- again, because of a fire hazard.