As you probably know Microsoft releases set of DST patches for their systems every year at December .
To avoid DST calendar issues make sure to install/deploy the following updates to entire organization.
Microsoft Windows Server and Windows XP/Vista Clients : KB 955839
Microsoft Exchange Server and outlook 2000/2003/2007 Clients:KB 941018 make sure to read MS DST Blog
The country that was skipped in MSÂ Day Light Saving update are Argentina/Brazil and Chile.
Daylight saving time begins: Read more
Update KB933360, makes update KB931836 to fail
Go to Start >Control Panel > Add remove programs
Mark Show updates.
Find KB933360 and press remove.
Read more