A hotfix is available to update the Daylight Saving Time for the “(UTC) Casablanca” time zone for Windows Operating Systems
Morocco will observe daylight saving time in 2010. This hotfix updates the DST start and end dates for the “(UTC) Casablanca” time zone.
More specifically, this hotfix sets DST start date for Morocco at first Saturday of May 2010 at 23:59:59.999 and DST end date at first Saturday of August 2010 at 23:59:59.999
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB982615.