Newsvine - Time Change to Bring Computer Glitches:
"For three weeks this March and April, Microsoft Corp. warns that users of its calendar programs 'should view any appointments ... as suspect until they communicate with all meeting invitees.'
Wow, that's sort of jarring — is something treacherous afoot?
Actually, it's a potential problem in any software that was programmed before a 2005 law decreed that daylight-saving time would start three weeks earlier and end one week later, beginning this year. Congress decided that more early evening daylight would translate into energy savings.
Software created earlier is set to automatically advance its timekeeping by one hour on the first Sunday in April, not the second Sunday in March (that's March 11 this year).
The result is a glitch reminiscent of the Y2K bug, when cataclysmic crashes were feared if computers interpreted the year 2000 as 1900 and couldn't reconcile time appearing to move backward. This bug is much less threatening, but it could cause head-scratching episodes when some computers are an hour off."