On Monday an advocacy group reported it had bought the hard drive in the Nigerian capital of Lagos and found a 2001 file with several dozen names of children and parents in the state program along with their location and some billing information. The Wisconsin Department of Health and Family Services isn't sure how that happened, a spokeswoman said.

"Right now I can't confirm whether that's our hard drive," said Stephanie Marquis, adding the drive didn't seem to match department records. "Obviously we have really serious concerns about the fact that this information has gotten into the public domain."

The case is a reminder of the perils of lost privacy in an age when bits of data - and even computers themselves - are traveling the world.

The Basel Action Network, an environmental group in Seattle, bought the hard drive along with several others in a Nigerian market and then had them analyzed to see what data was still on them, coordinator Jim Puckett said. The Action Network, he said, was trying to call attention to a related issue, the dumping of potentially toxic electronics from Wisconsin and the rest of the country in poor nations like Nigeria.

"This kind of data is obviously private," said Puckett, whose group posted the data on its Web site but blacked out the names of children and parents. "There was just way too much information that was not erased."

Puckett's group estimates that 400,000 computers and monitors - a large percentage of them junk - show up each month in Nigeria. Newer, working models like the mysterious hard drive from Wisconsin are resold and broken equipment is thrown into dumps, where it can release toxic pollutants like heavy metals, Puckett said.

In Lagos dumps, Action Network also found computers with tags from the Wauwatosa School District and a Wisconsin hospital, he said.

"It's a double question of responsibility. It's the environmental dumping and it's the privacy data," said Puckett, whose group has acknowledged that the previous owners of the computers haven't necessarily disposed of them improperly.

The Action Network also released a resume found on the hard drive, and Marquis confirmed that the man named in the resume was a former intern and later full-time accountant at the department. The former employee did not return phone calls from a reporter, but Marquis said he had told department officials that he hadn't sold a personal computer or put department records on other computers.

"It appears to be the type of information that obviously our department would handle," Marquis said of the files on the hard drive. "Ethically and legally this isn't information we would release."

Marquis said specs on the Nigerian hard drive didn't match the Health and Family Services Department's general equipment records, records of machines used by the former employee or old computers sent to UW-Madison's SWAP surplus shop to be sold or scrapped.

Marquis said the department is seeking more information, as well as the hard drive and data themselves, from the Action Network. Department employees sign agreements to keep data confidential and can be fired and face legal action if they fail to do so, she said.

Puckett said the hard drive bought by Action Network had probably only been reformatted, erasing the drive's directory but not its data, which left the data easy to retrieve.

Marquis said before 2003 the Health and Family Services Department erased the hard drive's directory only, but that in 2003 the department started completely erasing drives. Now if the files cannot be totally erased the drive is destroyed, Marquis said.

If the SWAP shop resells a computer, employees there again completely erase the hard drives, manager Tim Sell said. Computers that can't be sold are turned over to the state Department of Corrections, which would in turn be responsible for destroying or erasing them, he said.

State Department of Administration spokesman Scott Larrivee said state computers are replaced about every four years. Agencies are supposed to follow the pattern of erasing their own hard drives and equipment before sending it on to a group like SWAP to be erased again and disposed of, he said.