This weekend's early switch to daylight-saving time was billed as a little re-enactment of the Y2K computer problem at the turn of the millennium. And as it happened, the daylight bug appeared to have equally minor results.

Among the problems that were reported: Some customer-service call centers struggled to open at the proper hour. Calendar software inconsistently displayed meeting times.

But for the most part, the software patches and other tweaks applied by technology administrators worked as planned.

"It was not very serious, but a lot of work had been happening in the last weeks or two months to prepare for all this," said Julien Courbe, managing director of the financial services practice at BearingPoint Inc., a technology consultancy. "I think the work was comprehensive enough."

Courbe said his team at BearingPoint fixed the daylight-saving rules on 25,000 servers for its customers before the changeover and ended up with just a dozen "causing trouble." Usually those were in older programs, he said.

Like us humans, computers had to adapt to being told that daylight-saving time no longer begins the first weekend in April. The switch (along with a one-week extension of daylight time beginning this fall) stemmed from a 2005 federal law that sought to save energy by shifting more natural light to the evening hours.

Most home PCs got the time patches sent automatically, but users without automatic updates who now sport erroneous clocks should visit their providers' Web sites (such as www.microsoft.com/dst2007). People with Windows 2000 machines or older ones need to make their fixes manually.

If corporate tech administrators had done nothing, computers programmed before the 2005 law would have kept standard time until April 1. Nothing dire was likely to happen, unlike the computer crashes feared when the Y2K bug made machines think 1999 had given way to 1900. Still, being an hour off could disrupt calendaring software and transaction processing.

For example, some financial networks require that multiple machines coordinate, and an errant computer could screw it up. That's why the New York Stock Exchange and the Nasdaq Stock Market ran tests Sunday before pronouncing their systems fit for Monday's trading sessions.

But while the markets ticked on as usual, not everything was running correctly.

Anthony Hersey went to the Office of the City Clerk in New York on Monday to get a marriage license, and noticed that its computer-controlled time stamp said 7:50 a.m., even though the office didn't open until 8:30.

At NetTeks Technology Consultants Inc. in Boston, founder Ethan Simmons said the phones were "ringing off the hook" with problem reports, including some in automated communications systems. In a few instances, a company's network was an hour late in releasing calls to customer-support staff at the opening of business, leaving the "agents sitting around twiddling their thumbs," Simmons said.