Since June 2005, there have been at least 29 high-profile cases of misplaced or stolen laptops with data such as Social Security numbers, health records, and addresses of millions of people, according to the Privacy Rights Clearinghouse, a San Diego-based nonprofit that tracks data thefts.

However, protecting even the most sensitive information stored on laptops is not difficult with encryption technology. Encrypting the data renders it nearly impossible to access without the proper credentials, security experts say, and companies should not let laptops leave the premises without being encrypted.

"It is shocking how many of these are stolen laptops and the fact that the users of the laptops did not use encryption to secure the data," Beth Givens, director of the Privacy Rights Clearinghouse, said of recent data losses.

In most cases, the laptop itself, not the personal information on it, was the likely target of the theft. But there's almost no excuse for not following proper procedures to keep sensitive information stored on laptops safe.

The portable computers are usually protected by passwords needed to boot them up, but the data on their drives are still accessible. Encryption scrambles the information and renders it useless without the digital key that decrypts the data.

Many encryption tools are available, including software as well as specialized chips. But many people are reluctant to use them because losing the key can make it hard to access the data, and the programs can slow down data access, said Alan Paller, director of research at the SANS Institute.

For them, Microsoft's Windows Vista operating system, out late this year for businesses and early next year for consumers, will make encryption easier because it is built into the system.

Some companies that have lost laptops have begun implementing improved security measures. For example, Ernst & Young, whose highly mobile consultants use 30,000 laptops, is encrypting all contents on the computers, according to a company spokesman. After a very public laptop theft that endangered the personal data of more than 26 million U.S. veterans, the Veterans Affairs Department said it plans to recall every laptop to make sure the security programs are current.