WADST: Rebasing Calendar items for the extended DST period

I was contacted recently by a WA customer who had concern that calendar items weren't rebasing correctly. He emailed me with the following:

"...Can you please test and report on the recently released Outlook Time Zone Data Update Tool (see KB931667) as my testing shows it does not work properly for the extended DST period for WA for this summer. It should just update entries between 28-Oct-2007 and 1-Dec-2007 (the period for which DST has been extended this summer compared to last summer) but instead it updates entries right through to 30-Mar-2008...."

In his instance only the client DST patch KB933360 for Windows XP had been installed with no recent DST patches installed on the Exchange 2003 SP2 servers and they still had last summers DST definitions. All their clients were using Outlook 2003 SP2.

Therefore, our guidance is:

* If you believe you never had 929120, just rebase using the tool. It should all be good.

* If you believe that your calendar is correct when viewed with 929120 installed, install 933360 and rebase using /ONLYRECURRING. Then, manually fix up single-instance items between the [Last Sunday in October and the First Sunday in December].

The customer tested the above guidance and found that it worked for him. That said please show due diligence and test this first in a test network that mirrors your production network. Please do not apply to production first without testing - otherwise you do so at your own risk.