Xyzzy

The US has changed the start/end of Daylight Savings Time from 2007. This adds about four weeks per year to DST. Microsoft, has implemented patches to most of its current operating systems. Unfortunately, those patches change the DST behaviour for *all* years, not just 2007. This will wreak hacov with date/time information for items that are in the approximately four weeks per year that are now part of DST but that were not before. In other words, Microsoft has changed history by one hour for about four weeks/year.

This problem is glossed over on the official Microsoft "Preparing for Daylight Saving Time changes in 2007" web page. A more detailed discussion of this can be found in the Microsoft Visual Studio site, where on this page, the following text appears:This has, of course, caused lots of problems, even for Microsoft products like Outlook. One person's personal rant about this can be found here.

For those of you who see one hour of difference as nothing to worry about, think of some of the implications:

• The *dates* of some things that occurred near midnight might change
• When requested, the operating system returned one date/time value before the patch and a different value when presented with the same request after the patch.
• Applications can fail or report odd errors, when things that should never change do change (I've dealt with a number of these at work).
• "Fix it yourself if you want it fixed" is a very sloppy way to work.

Oh -- Linux appears to have gotten this fix right. The glibc table for date/time changes even accounts for leap seconds.

cordelli

For outlook users, you may need to apply an additional patch in addition to the ones that are for Windows, details are available here

http://support.microsoft.com/kb/931667/

Efrem

For Macintosh users:

OS X 10.4: Version 10.4.5, released February 2006 (a year ago), includes DST updates for the U.S., Canada and many other countries. A February 2007 update, available separately or in Version 10.4.8, adds January 2007 changes for Australia, Brazil, Alberta (Canada) and a few other regions. All updates are year-sensitive so they do not affect dates/times before 2007. (You may also need to install a Java update to make everything compatible.)

OS X 10.3: All the above changes are in the DST Update released February 2007. Update to Version 10.3.9 first if not already on it. This update is also year-sensitive. (You may also need to install a Java update to make everything compatible.)

Information on all the above is available on Apple's Web site, along with all the downloads, if Software Update hasn't already found them and told you about them. (It should have.)

Earlier versions of OS X: Deselect the option to set date and time automatically, then set local time as needed.

OS 9 and earlier: Deselect the option to observe DST automatically, then set DST on or off as needed. (The "Classic" OS 9 environment in OS X uses OS X time/date settings, so it need not be touched.)

Xyzzy

Micro$oft is just plain lazy

Bobster

This brings happy memories of Windows 95 stupidity. At the end of DST, the clock went from 2am to 1am. One hour later, the clock went from 2am to 1am. And it kept doing that over and over until I made it stop.

redburgundy

alanh

Linux keeps the system clock at UTC all the time, and just displays a time adjusted for the local timezone.

The problem with Windows (and DOS) is that it's always stored the time as local time. Since Windows does it that way, most programs also do it that way.