Normally the switch to daylight-saving time isn't a big deal, but this Sunday, Jeff Ronner has to put people on the case.
Ronner is a San Francisco-area field services manager for technology outsourcer Perot Systems Corp., and he handles computer systems for a big Perot client, Catholic Healthcare West. This week he was putting final touches on his plan to make certain that Catholic HealthCare's voicemail systems and other networks recognize daylight time.
Those computers, like those of all but the most recent vintage, probably were programmed to believe that daylight-saving time begins the first Sunday in April and ends the final Sunday in October. Those rules, in place for two decades, were overturned by a 2005 U.S. law that extended daylight-saving time by three weeks in the spring and one week in the autumn.
This is nice for after-dinner strolls and might even save some energy (which was Congress' motive), but the computing industry has had to scramble. Many people only recently realized the change would even impact computers.
"This has been a little bit of a sleeper issue," said Brian Mulford, chief technology officer at Regulus Group LLC, which handles payments and other transactions for large consumer companies.
Computing vendors developed and sent out patches that alter how software deals with daylight-saving time - which should cover most home PC users. Those who rely heavily on calendar programs should visit their software providers' Web sites for advice.
"The average person, John and Jane computer user, is unlikely to see much of a problem, if anything," said David Keller, founder of Compu-Doctor, a computer-help provider in Florida.
But in many complex networks with a range of newer and older equipment, on-the-fly tweaks sometimes have been unavailable. That has forced systems engineers to study how various computing applications deal with time, and make manual fixes if necessary.
The process reminded some people of the planning for the widely feared Year 2000 bug, even if the effects of this glitch - computer time is an hour off - appear way less threatening.
"We're going back to our Y2K lists to refresh our memories, to see what we did where and whether any of those areas are applicable to this, and sometimes the answer is yes," Ronner said.
Some of Ronner's telecom engineers will be able to dial in remotely Sunday to make sure the time change went seamlessly at Catholic HealthCare's offices and hospitals. But in some cases they might have to drive to a hospital to make a manual update.
Otherwise, Ronner said, things like voicemails about patient care might get an erroneous time stamp.
"There's a lot to consider," Ronner said. "Something that seems as simple as turning a clock back has amazing and extensive implications in everything you touch here, because so many things are date- and time-stamped."
Mulford said one potential issue for Regulus' customers was that improperly updated computers in financial services companies could register deposits or other transactions on the wrong day, if being one hour off made them miss some daily cut-off point.
He said customers' systems were patched and secured by January - though just to be safe, he plans to have extra support staff around this weekend in case clients have time-related problems. All that remained on Mulford's checklist this week was ensuring that his company's own employees' PCs and portable devices were up to date.
"It's the random printer out there with a time stamp that we're fixing this week," he said.
Some computer glitches may not show up until Monday, the first business day under the new daylight-saving schedule. But computing experts don't expect major problems to erupt.
Even Ronner, with his meticulous plan for dealing with the switch, doesn't seem too worried. When asked what he'd be doing early Sunday as standard time changes to daylight time, he replied: "I'm sleeping in. I'll only be called if something doesn't work."