"To comply with the U.S. Energy Policy Act, this year’s Daylight Saving Time (DST) will start three weeks earlier (March 11) and end one week later (November 4) than in 2006. This change affects many operating systems and applications that interact with dates and time."
Because the Daylight saving time differs from previous years, you must update your computer (not just changing the clock). For details on how to update, please see the webpage below.