The law of unintended consequences may rear its ugly head next week when IT administrators face the computing ramifications of the change in daylight-saving time.

As a part of the Energy Policy Act of 2005, legislators moved the daylight-saving start time three weeks ahead and pushed the end time one week back. The earlier start date begins on Sunday.

Because so many systems and applications automatically adjust for daylight-saving time, IT experts have warned that the business world may experience problems with time-based systems, including calendar applications such as Outlook, billing applications and in-house software.

“I don’t think it will be anything cataclysmic but it will definitely cause disruption,” said Don Leatham, director of solutions and strategies at PatchLink. “There will be appointments missed, there will be invoices that will be incorrectly timed, and depending on the industry, there might be some challenges in getting through this.”

Latham and other security and business-continuity experts have warned IT workers for several months about the need to properly patch and configure all of their systems in advance of the daylight-saving shift.

“From our standpoint, we feel that it is something that definitely needs consideration by IT departments,” Leatham said. “There are a lot of critical business processes that are time-based and coordinated across multiple time zones. So making sure that there are no critical business applications that are not correctly patched and able to handle this switchover is an important thing for all IT departments.”

Last month, Gartner released a report cautioning organizations to prepare for the change, while a variety of analysts have dispensed similar advice. And while awareness is relatively high about the situation, Leatham wondered if some organizations have considered all of the angles of the problem, including custom software that may be time-based.

“We feel that there is a high level of awareness about this, so we don’t feel that awareness is a problem; but being able to consider this from every angle could be a challenge. To make sure that they don’t leave anything out there that shouldn’t be patched, but should have been patched, could be the challenge,” he said.