The witching hour

Will your computer be ready when daylight saving time comes?

In case you didn't know, that will happen four weeks earlier this year, thanks to congressional fiat.

And though "springing forward" in March instead of in April might not seem like a big deal, consider this:

Every e-mail you send is stamped with the time it was sent, as are important transactions such as the automatic deposits you make to a savings account or payments you make online on a credit card balance.

In some cases, your computer's clock being off by an hour can make a difference, and many computers are still operating under the assumption that d aylight s aving time is coming April 1, not March 11 -- meaning that precious hour could very well be lost for you.

So what to do? Start checking all of your computer hardware and software now, to see what needs to be fixed before you run into a problem, said William J. Kryouz , network services manager at law firm Goodwin Procter LP.

"You have to take an inventory of all of your stuff and check with the vendors to see if you should care about the daylight saving time issue," said Kryouz, whose job is to make sure the firm's computers and network run smoothly. He's nervous because little has been reported in the news media about the impending daylight saving time bug, and with good reason: He worked for a company that didn't take adequate precautions against the Y2K bug, and its computer network crashed as a result.

The first thing to do, he said, is start checking with the makers of whatever computer equipment you or your company use. The fewer gadgets there are, the easier that should be.

For a home user running one computer on the dominant Windows operating system, a quick visit to Microsoft's website will tell you whether you have anything to worry about: If your computer is running Windows XP with the Service Pack 2 upgrade, or Windows Vista, carry on as usual -- your system will update itself. But if you're running XP and didn't take the SP2 upgrade, now's the time to do so.

With older versions of Windows, such as Windows 2000 or NT, you need to visit Microsoft online to get specific instructions. Or you could wait until your clock is inaccurate and change it manually.

Microsoft's top rival, Apple Inc., says its OS X operating system was "patched" with a fix for the problem months ago. Anyone running the system should have already gotten an automatic update and won't have a problem, said Anuj Nayar , a spokesman.

Congress approved the change in daylight saving time two years ago, to improve energy efficiency. Instead of starting on the first Sunday in April, as it had, this year it will start on the second Sunday in March. With one more month of "longer" days and more sunlight during waking hours, the thinking goes, consumers will use less energy.

But the impact on computer systems, many of which perform tasks on a schedule dictated by internal clocks, got little attention.

Fixing the problem probably won't cost companies much, Kryouz said, because in many cases all that's required is a software patch that can be downloaded for free. But if you're running a network that includes many computers or other electronic devices with their own clocks, expect to spend more time and money on the problem, he said.

The change in daylight saving time is no Y2K bug, the experts agree. Approaching 2000, technology experts became aware of a startling problem: Computer clocks were programmed to recognize only the last two digits in a year, for example reading 1999 as just '99. When the year changed to 2000, then, it was feared those clocks and the computers they were tied to would shut themselves down.

To the average person, the Y2K furor seemed much ado about nothing, but a tremendous amount of work was done and money spent over several years to avert what could have been a catastrophe. The federal government alone said it spent about $8.5 billion; other sources pegged the worldwide cost at about $200 billion.

Keith Reed can be reached at reed@globe.com.

(Correction: Because of reporting errors, a story about daylight saving time that appeared in Monday's Business section misspelled the name of William Kryouz and the law firm where he works, Goodwin Procter LLP. It also used the former name of Apple Inc. and misrepresented the scheduling change for resetting clocks this year. The change to Eastern Daylight Time occurs on March 11, three weeks earlier than it did last year.)