Timing and scheduling issues after a daylight saving time update or time zone update
The start dates and the end dates for daylight saving time (DST) in many countries change from year to year. Additionally, some countries may change their DST recognition policy or may change the local time offset from Coordinated Universal Time (UTC). In this scenario, some schedules and some applications that depend on date and time calculations may have a problem.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB2400550.