Useful update: Most computer and software manufactures now have notices on their web sites as to the computability of their products. You may have to look around a little, but by knowing the model or version of the product you can usually find out if your home or office computer and software are going to be all right when the dreaded day comes.

Y2K (shorthand for the Year 2000) is fast approaching. It is an arbitrary milestone, simply the changing of the calendar. The new millennium doesn't begin on 1 January 2000 but on 1 January 2001. The date is supposed to represent 2000 years from the birth of Jesus, but actually that landmark has been passed, as he was probably born (on who knows what day) in 4 B.C. But Millenium Fever is hot, not only because some predict Armageddon, but also for a reason no one foresaw a few decades ago.

The problem is that when computers were still new they didn't have much memory, so programmers used only two digits for dates instead of four. 1998 in many computers is 98. What will happen when the date reads 00? Many computers will assume that it is 1900. If you are getting a social security check, paying a water bill or withdrawing money the computer will assume that you haven't been born yet. Chaos is predicted.

Some think that things will be all right, but wise people look ahead. The problem is enormous because:

• Most computers running our affairs are written in older languages with two-digit dates and those languages are no longer widely known by programmers.
• There are not enough programmers to fix this problem.
• Even if the problem is fixed, say at your bank, as soon as its computer talks with an infected computer it can be infected all over again.

Actually, there are three dangerous dates looming.

• 9 September 1999. Many programs wrote 9/9/99 as the Date That Will Never Happen. Many things will expire on that date.
• 1 January 2000. The big one, as discussed above.
• 29 February 2000. Leap years happen every four years, but only every four century (part of the Gregorian reform that makes the calendar more accurate). 1900 was not a leap year. Many computers don't know this.