At first blush it may seem like no big deal: clocks in the US will move ahead by an hour three weeks earlier than usual this year. But for today's networked businesses, the simple change could mean complex problems if IT shops aren't prepared, industry experts say.

The trouble goes beyond missed meetings and messed-up schedules to errors within time-reliant applications that are critical to a company's business -- processes such as operating room scheduling, billing and contract deadlines and ensuring record compliance, for example, could be at risk. Any applications dependent on timestamps will run into trouble after March 11, the new day for the daylight-saving time change, if actions aren't taken.

For more than two decades, daylight-saving time has begun on the first Sunday of April and reverted to standard time on the last Sunday in October. But beginning this year, due to the US Energy Policy Act of 2005, the daylight-saving schedule will be extended by a month, with the period beginning on the second Sunday in March and ending on the first Sunday in November. Legislators backing the change say it will save some 100,000 barrels of oil a day.

But the change also could throw a wrench in IT systems set up to automatically handle the old daylight-saving schedule. As a result, IT professionals need to take a close look at their systems and applications to determine which could be off when the change occurs and then take the necessary steps to correct them.

"My fear is that a lot of people aren't going to realize this is a big issue until months down the road when they say, 'Oops, why aren't these dates lining up,'" says Scott Metzger, CTO at consumer credit management firm TrueCredit in California.

Mike Sly, a senior IT consultant at IT integrator Evolving Solutions, agrees. Like a lot of vendors and service providers, Evolving Solutions has sent alerts to customers, many of whom haven't been aware of the change.

"It's really more pervasive than [Y2K] ever was," Sly says. "It will impact anything that has to do with dates and times and scheduling -- transportation, hotels, airlines, sales. It's just everywhere. ... It blows me away that not many people seem to be all that aware of it."

Vendors have been focused on the issue and want to help customers make the transition. Most major IT vendors including Cisco, IBM, Microsoft, Novell, Red Hat and Sun, have Web pages dedicated to the daylight-saving change that outline what fixes are necessary for their products. Smaller vendors, too, are making sure their products are updated.

PeopleCube, for example, began shipping updated releases of its resource scheduling and calendaring software that comply with the new daylight-saving dates late last year. On a larger scale, Microsoft addressed the issue by embedding the updated daylight-saving rules into Vista and it has patches available for Windows XP SP 2 and Windows 2000. Organizations running Windows XP SP 1 or Windows NT, however, will have to use a workaround that can be found on the Microsoft Web site .

In its daylight-saving directives, Cisco notes that the repercussions of the change extend beyond scheduling and into areas such as security and monitoring .

"This change can have a major impact on event correlation activities that are performed as part of normal operations troubleshooting and monitoring," the Web site says. "For security-related devices, where logs are captured, correlated, and stored for future reference, this time change could render them incorrect for situations where they need to be recalled to rebuild a sequence of events. The incorrect timestamps might not be an issue for events that get immediate action. However, in the future, these events would reference incorrect times."

TrueCredit's Metzger says he and his team have been working since October to make sure their systems move smoothly into the new time. Metzger says the "lion's share" of work they need to do centers around updating Java virtual machines, a task that can be tricky and time consuming because of the variety of Java Runtime Environments out there.

The good news for Metzger is that TrueCredit has consolidated its physical environment by running Azul's multicore Compute Appliances, which offload Java workloads to reduce the strain on traditional application servers.

"We just have to do a patch update to four physical machines, which are centrally managed through one console," Metzger says. "Prior [to Azul] we had multiple disparate systems, but consolidating everything onto a fewer number of physical units and having those machines centrally managed has made this particular issue easier to handle."

Rich Debrino, CIO for Everett, Wash.-based Advances in Technology, which handles IT for a variety of healthcare organizations, including parent company Compass Health, notes that systems tied to external network time servers should have few problems.

"Most proactive IT execs who run a big shop are going to use some kind of network time protocol tied either internally or externally," he says. "If you're using something that's tied externally to a network time server then who cares about daylight-saving time changes because the network time servers are going to be updated anyway."

Internal time servers should also help keep things in line. "Make sure you've got your [time] servers updated, then everybody else, when they log on to the network, should automatically update," he says.

John Halamka, CIO at CareGroup Health System in Boston, says his staff is patching Windows XP, Outlook and Exchange in accordance with Microsoft's directives and also is reviewing what other fixes need to be made.

"For applications that have time-sensitive stamps [hospital orders, electronic medical record notes] we surely need to fully understand what layer of the system is playing a role in the timestamp and assure it is fixed," he says.

From initial review it seems that most applications derive times from the server operating system, "which use time servers and thus require no patch," Halamka says, adding that the daylight-saving change pales in comparison with Y2K.

"We spent two years and US$20 million on Y2K. This issue has no budget and will take two months," he says.

Nevertheless, industry experts agree that IT managers need to address the issue to avoid glitches.

"The problem is very wide and not very deep," says Steven Ostrowski, a spokesman for Computer Technology Industry Association. "It's going to cause a lot of little headaches instead of big Y2K-type issues. But people need to be prepared."