New York ? When daylight-saving time starts earlier than usual in the United States come 2007, your VCR or DVD recorder could start recording shows an hour late.

Cell phone companies could give you an extra hour of free weekend calls, and people who depend on online calendars may find themselves late for appointments.

An energy bill President Bush is to sign Monday would start daylight time three weeks earlier and end it a week later.

And that has technologists worried about software and gadgets that now compensate for daylight time based on a schedule unchanged since 1987.

“It is unfortunately going to add a little bit of complexity to consumers,” said Reid Sullivan, vice president of the entertainment group at Panasonic Consumer Electronics Co. “In some cases, depending on the product, they may have to manually increase or decrease the time.”

The upcoming transition evokes memories of Y2K, the Year 2000 rollover that forced programmers to adjust software and other systems that, relying on two digits for the year, never took the 21st century into account.

“It wouldn’t be a society-wide catastrophe, but there would be a problem if nothing’s done about it or we try to move too quickly,” said Dave Thewlis, executive director of a group that promotes standards for calendar software.

Newer VCRs and DVD recorders have built-in calendars to automatically adjust for daylight time. Users would have to override them, switching to “manual” to ensure shows continue to record correctly.

Computers with Microsoft Corp.’s Windows operating systems would need to obtain updates. Though most affected applications likely would be taken care of by the Microsoft fix, calendar systems would need to be checked to ensure that appointments already entered were properly adjusted.

Some electric utilities have advanced meters to adjust rates based on peak and non-peak hours, and studies would be required to determine if any modifications would be needed. The telecommunications industry, meanwhile, must ensure that its clocks would be properly adjusted to bill customers appropriately.

Adding to the complications is the fact that many computer programs now treat U.S. and Canadian time zones as the same. If Canada doesn’t adopt the new dates, too, Windows, calendars and other software would have to learn additional zones.

Technologists sounded louder alarms as the Year 2000 approached. The programming shortcut caused some computers to wrongly interpret 2000 as 1900, potentially fouling systems that control power grids, air traffic, banking systems and phone networks.

Businesses and governments around the world threw some $200 billion at the problem, and the transition occurred without any worldwide disaster, even leading some critics to suggest they were victims of a big-money bamboozle.

The daylight-saving transition would be – at most – a mini-Y2K, with the effects of any failure far less reaching.

“We’re looking only at a one-hour difference versus setting back (the clock) 99 years,” said Randall Palm, of the Computing Technology Industry Assn.

No matter what happens, at least one thing is clear: Americans have largely become complacent and expect many clocks to change automatically because dates have been set for two decades, said Lauren Weinstein, a veteran technologist.

“Missiles won’t be launching but it’s still going to cause a lot of hassle,” he said. Risks grow when “things advance to the point where you expect things to happen automatically and you expect it to be correct.”