Why would daylight-saving time mess up my computer?

The U.S. Congress changed the daylight-saving schedule in an attempt to save energy.
John Foxx/Getty Images

Earlier this year, computer users and IT administrators in the United States and Canada braced for a mess. Some said a mini Y2K bug was going to throw networked applications into a tizzy and make "Lost" fans cry when they realized their DVR missed the show. Others said it was a simple fix for networks as long as companies were prepared, and that there was nothing to panic about. Much like the Y2K bug that was supposed to crash the world, this bug also had to do with time.

In 2005, the U.S. Congress mandated a change in the daylight-saving time schedule that took effect earlier this year. On March 11, we turned our clocks forward three weeks earlier than usual; on November 4, we'll turn them back one week later, the idea being we'll get some energy savings out of the longer period of evening sunlight. In March, many feared that any device that automatically updated its time to spring forward might have a little problem -- the new daylight-saving start date. This included computers, cell phones, smartphones, PDAs, DVRs, "smart home" systems, time-controlled thermostats, high-tech watches and clocks and countless other gadgets.

Advertisement

You might be thinking that since the device updates itself by synching with some omniscient world clock, it'll still get the correct time, adjusted for the correct daylight-saving date. Because, you know, it's omniscient. In reality, that world clock is a whole bunch of "time servers" maintained by various agencies, and they all serve up a single time: Greenwich Mean Time, or "universal time." Once your device gets the Greenwich Mean Time, it calculates the correct time for your location by adding or subtracting hours based on your time zone and any daylight-saving adjustments for which it's been programmed. Any computer that was programmed before 2005 thinks daylight-saving started the first Sunday in April, not on March 11, and ended in October, not November.

When the bug first hit in the spring of 2007, many people thought they would have to change their clocks four times instead of two -- twice in the spring and twice in the fall -- to make up for the automatic, but incorrect, daylight-saving time adjustments. The one-hour shift had, and still has, the potential to affect lots of gadgets around the home. Your DVR might record the wrong shows if it's not connected to a service provider or if that service provider hasn't automatically downloaded a patch to your machine. Your thermostat might drop the temperature at the wrong time. It could turn out to be a hassle, depending on how automated your home is. Or you might not even notice it.

But the real problem with the time change has to do with businesses, their networks and any business-related applications you run on your own home computer -- Microsoft Outlook calendar reminders, for instance. We’ll look at how businesses are dealing with the change to daylight-saving time in the next section.

Advertisement

Time Change Problems

Downloading a patch can prevent computer clock chaos at daylight-saving time.
Photodisc/Getty Images

The possibility of real chaos arises with time-sensitive payments and applications like scheduled meetings, scheduled stock trades, scheduled bank deposits, time clocks, and large networks -- especially international ones -- that rely on a variety of synched devices to operate properly. Only North America and Bermuda are abiding by the U.S. time change, so companies with an international presence are at particular risk of missing some important conference calls and messing up the timing of transfers. Time clocks might show that employees clocked out early or late; sales orders may be recorded incorrectly; and bank deposits could post at the wrong time. Scheduled stock sales and purchases that happen just an hour off could mean big losses. Airlines could end up displaying incorrect departure and arrival times, and cell-phone companies might charge you peak rates for calls you place at off-peak hours.

But if everyone plans ahead, most of these issues can probably be avoided.

Advertisement

As a consumer, as long as you double check your meeting times, and the companies you rely on have dealt with the necessary updates, you shouldn't run into too many problems. Fixing your computer, if it's pretty new, just means installing a patch. If you run Vista, this doesn't affect you at all, since Vista came out after 2005. It's already programmed with the new daylight-saving dates. If you run Windows XP with Service Pack 2 and you allow for automatic updates, the problem on your computer is probably already fixed or will be soon. Microsoft released the patch on February 13 that will set your machine to change the hour at the right time. If you've switched off automatic updates, you'll have to go to Microsoft Daylight Saving Time Help and Support Center and download the patch yourself. Mac also has daylight-saving patches available at Apple Daylight Saving Time 1.0.

IT system administrators definitely have the most work to do, downloading individual patches for each different piece of hardware and software and somehow getting everything to synch up, even though some parts of the network will update automatically and some won't. But all major software companies have released patches to address the problem. However, with many businesses running custom Java applications, the universal patch may not cut it, and tech folks may find themselves working overtime to fix each individual application by hand.

Still, most new software is covered. Patches for older equipment will be harder to come by. If your PC runs an operating system that's pre-Service Pack 2 (pretty much everything older than XP), your service agreement has run out. You can still get a patch, but you'll have to pay for it. Older Windows-based servers and mobile devices are in the same boat, and Mac patches only go back to Mac OS X Panther.

If you have a VCR with a clock that updates itself automatically for daylight-saving time, you should probably just plan on viewing the wrong time for a while. Or you can change the time manually. Regardless, everything should be back to normal on November 4.

For more information on daylight-saving time and related topics, check out the links on the next page. 

Advertisement

Lots More Information

Related HowStuffWorks Articles

More Great Links

  • Buettner, Michael. "Cha­nging times are coming." Association of Information Technology Professionals. Feb. 13, 2007. http://www.aitp-charleston.org/
  • ­Davidson, Paul. ­"Time change could catch businesses snoozing." USA TODAY. Feb. 9, 2007.­ http://www.usatoday.com/tech/news/2007-02-09-daylight-usat_x.htm
  • ­"Daylight-saving bug could foil computers." CNN.com. Feb. 19, 2007. http://www.cnn.com/2007/TECH/02/19/daylight.saving.bug.ap/
  • ­­Evers, Joris. "Wake up to the 'daylight-saving' bug." CNET News.com. Feb. 16, 2007.

­

Advertisement

Loading...