January 4, 2000
Web posted at: 5:48 a.m. EST (1048 GMT)

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(CNN) -- Armored trucks are carrying billions of extra dollars, distributed to banks in case of Y2K panic, back to the U.S. Federal Reserve. Stock markets opened without major hitches on their first day of trading in the new century, and some posted all-time highs.

Much of the world has returned to work and found it was mostly business as usual, despite the calendar rollover to the year 2000. But some information technology experts warn that the Y2K bug is still lurking in many systems.

They say that the biggest risk was never to power grids, missile systems or telephone exchanges, but rather to complicated backroom systems on which the world's corporations and governments run. And they add that the vast majority of year 2000 computer problems won't turn up for days, weeks or even months.

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"Now is the tough time. The next few months are going to be the toughest Y2K time," said Dale W. Way, bug point man at the Institute of Electrical and Electronic Engineers.

"It is possible that bugs will manifest themselves in the coming days and weeks," said Ed Yourdon, a computer programmer and author who for years has warned the world -- on his Web site and in his book "Time Bomb 2000" -- of a calamity stemming from the rollover to 2000.

Issuing a warning similar to that of the U.S. government's own Y2K experts, Yourdon told The New York Times that while many large companies and utilities have cleared up their Y2K defects, there was less work done by smaller firms that use older software.

Many minor glitches have already shown up. Driver's licenses could not be issued in nearly half of New Mexico's motor vehicle offices. A vital payroll computer died at an Alabama company. A small part of a Danish bank's payment system was erased. Digital meters on taxis stopped functioning in many Chinese cities.

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At greatest risk in the private sector are the accounting, inventory, invoicing, billing and other systems integral to survival -- a crazy quilt of interconnected programs often cobbled together over decades.

Such "custom applications," also common in government agencies, are nothing like the control systems at power and water plants, which are typically spare, easy to maintain and fortified by built-in redundancy.

Instead, they tend to be a mishmash of different software languages riddled with updates and patches applied over decades like digital duct tape that experts say make them especially susceptible to Y2K errors.

"Every large company says they have some software that they run routinely without even knowing what it does," Way said. "They are afraid not to run it -- because they're afraid of screwing up if they don't."

That's why tampering with such code to try to purge it of Y2K bugs can often introduce new unrelated errors. Programming is an art, not a science, and not all programmers are Picassos.

Errors also may not occur until triggered by a particular event.

"A program whose job is to track the pressure in a chemical plant's boiler ... may not activate until a certain temperature is reached," said Norman Dean, director of the Center for Y2K and Society, a Washington public interest group. "And that may not happen until next week and it may not happen until next year."

Infected systems are apt not to blow up, but rather to degrade over time -- linked in many cases to monthly report generation or billing cycles -- and often not even be easily identifiable as Y2K-induced.

"Y2K effects will linger far past January as a patina of rust" on information systems, predicted Robert X. Cringely, a Silicon Valley commentator.

While many governments dismantled Y2K bunkers Monday and a World Bank-funded international Y2K clearinghouse in Washington canceled all further press briefings, big companies remained vigilant.

"Our feeling here at AT&T is that we won't close the book on Y2K until February 29," said company spokesman Dave Johnson. "First of all, we need all our billing systems to run a full cycle and then we want to take a close look at the leap year."

There's typically -- but not always --- an extra day in February every four years, and this leap year is particularly unusual.

Leap day 2000 is "the exception to the exception," explained Rick Weirich, the Postal Service's vice president for information technology.

Some computers may not expect a leap day this year, and thus skip ahead to March 1, he explained.

Because the actual year is slightly longer than 365 days, an extra leap day is added every fourth year.

But that still doesn't make things come out quite even over time, so leap days normally are skipped in years ending in 00. Except -- and here's the problem -- if the year ending in 00 can be divided evenly by 400 it still is a leap year.

So the Y2K computer problem simply will not go away. Due to the extra day issue, it will even nag us on December 31, 2000.

As programmer Lane Core likes to say in Internet columns that harangue what he considers mainstream media's simplistic coverage of the issue: "Y2K is not a one-time event. It's a chronic condition."

The Associated Press and Reuters contributed to this report.

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